diff --git a/lib/6to5/transformation/file.js b/lib/6to5/transformation/file.js
index c23360d713..e93a3bd07d 100644
--- a/lib/6to5/transformation/file.js
+++ b/lib/6to5/transformation/file.js
@@ -160,8 +160,8 @@ File.prototype.normalizeOptions = function (opts) {
 
   opts.blacklist = transform._ensureTransformerNames("blacklist", opts.blacklist);
   opts.whitelist = transform._ensureTransformerNames("whitelist", opts.whitelist);
-  opts.optional = transform._ensureTransformerNames("optional", opts.optional);
-  opts.loose = transform._ensureTransformerNames("loose", opts.loose);
+  opts.optional  = transform._ensureTransformerNames("optional", opts.optional);
+  opts.loose     = transform._ensureTransformerNames("loose", opts.loose);
 
   return opts;
 };
@@ -198,6 +198,12 @@ File.prototype.buildTransformers = function () {
   this.transformers = transformers;
 };
 
+File.prototype.debug = function (msg) {
+  var parts = this.opts.filename;
+  if (msg) parts += ": " + msg;
+  util.debug(parts);
+};
+
 File.prototype.toArray = function (node, i) {
   if (t.isArrayExpression(node)) {
     return node;
@@ -344,7 +350,7 @@ File.prototype.parse = function (code) {
 File.prototype.transform = function (ast) {
   var self = this;
 
-  util.debug(this.opts.filename);
+  this.debug();
 
   this.ast = ast;
   this.lastStatements = t.getLastStatements(ast.program);
@@ -357,23 +363,27 @@ File.prototype.transform = function (ast) {
 
   this.checkNode(ast);
 
-  var astRun = function (key) {
-    each(self.transformerStack, function (pass) {
-      pass.astRun(key);
-    });
-  };
-
-  astRun("enter");
+  this.call("pre");
 
   each(this.transformerStack, function (pass) {
     pass.transform();
   });
 
-  astRun("exit");
+  this.call("post");
+};
+
+File.prototype.call = function (key) {
+  var stack = this.transformerStack;
+  for (var i = 0; i < stack.length; i++) {
+    var transformer = stack[i].transformer;
+    if (transformer[key]) {
+      transformer[key](this);
+    }
+  }
 };
 
 var checkTransformerVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     checkNode(state.stack, node, scope);
   }
 };
diff --git a/lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js b/lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js
index 7a4011a79e..636c9b284b 100644
--- a/lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js
+++ b/lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js
@@ -12,7 +12,7 @@ module.exports = function (exports, opts) {
     return t.assignmentExpression("=", left, right);
   };
 
-  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+  exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
     if (file.isConsequenceExpressionStatement(node)) return;
 
@@ -29,7 +29,7 @@ module.exports = function (exports, opts) {
     return nodes;
   };
 
-  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+  exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!isAssignment(node)) return;
 
     var nodes    = [];
diff --git a/lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js b/lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js
index f72126415f..ce68e5c49f 100644
--- a/lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js
+++ b/lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js
@@ -8,7 +8,7 @@ module.exports = function (exports, opts) {
     return t.assignmentExpression("=", left, right);
   };
 
-  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+  exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
     if (file.isConsequenceExpressionStatement(node)) return;
 
@@ -27,7 +27,7 @@ module.exports = function (exports, opts) {
     return nodes;
   };
 
-  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+  exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!opts.is(node, file)) return;
 
     var nodes    = [];
diff --git a/lib/6to5/transformation/helpers/name-method.js b/lib/6to5/transformation/helpers/name-method.js
index ae86c91523..8df977dafb 100644
--- a/lib/6to5/transformation/helpers/name-method.js
+++ b/lib/6to5/transformation/helpers/name-method.js
@@ -4,7 +4,7 @@ var util = require("../../util");
 var t    = require("../../types");
 
 var visitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     // check if this node is an identifier that matches the same as our function id
     if (!t.isIdentifier(node, { name: state.id })) return;
 
@@ -17,7 +17,7 @@ var visitor = {
     if (localDeclar !== state.outerDeclar) return;
 
     state.selfReference = true;
-    context.stop();
+    this.stop();
   }
 };
 
diff --git a/lib/6to5/transformation/helpers/remap-async-to-generator.js b/lib/6to5/transformation/helpers/remap-async-to-generator.js
index 05924787da..1161832439 100644
--- a/lib/6to5/transformation/helpers/remap-async-to-generator.js
+++ b/lib/6to5/transformation/helpers/remap-async-to-generator.js
@@ -3,8 +3,8 @@
 var t = require("../../types");
 
 var visitor = {
-  enter: function (node, parent, scope, context) {
-    if (t.isFunction(node)) context.skip();
+  enter: function (node, parent, scope) {
+    if (t.isFunction(node)) this.skip();
 
     if (t.isAwaitExpression(node)) {
       node.type = "YieldExpression";
diff --git a/lib/6to5/transformation/helpers/replace-supers.js b/lib/6to5/transformation/helpers/replace-supers.js
index d4d59b056c..66048ab4d9 100644
--- a/lib/6to5/transformation/helpers/replace-supers.js
+++ b/lib/6to5/transformation/helpers/replace-supers.js
@@ -79,19 +79,19 @@ ReplaceSupers.prototype.replace = function () {
 };
 
 var visitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     var topLevel = state.topLevel;
     var self = state.self;
 
     if (t.isFunction(node) && !t.isArrowFunctionExpression(node)) {
       // we need to call traverseLevel again so we're context aware
       self.traverseLevel(node, false);
-      return context.skip();
+      return this.skip();
     }
 
     if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
       // break on object methods
-      return context.skip();
+      return this.skip();
     }
 
     var getThisReference = topLevel ?
diff --git a/lib/6to5/transformation/modules/_default.js b/lib/6to5/transformation/modules/_default.js
index d72f4bdb9c..ad36cbeed7 100644
--- a/lib/6to5/transformation/modules/_default.js
+++ b/lib/6to5/transformation/modules/_default.js
@@ -38,7 +38,7 @@ DefaultFormatter.prototype.bumpImportOccurences = function (node) {
 };
 
 var exportsVisitor = {
-  enter: function (node, parent, scope, context, formatter) {
+  enter: function (node, parent, scope, formatter) {
     var declar = node && node.declaration;
     if (t.isExportDeclaration(node)) {
       formatter.hasLocalImports = true;
@@ -63,7 +63,7 @@ DefaultFormatter.prototype.getLocalExports = function () {
 };
 
 var importsVisitor = {
-  enter: function (node, parent, scope, context, formatter) {
+  enter: function (node, parent, scope, formatter) {
     if (t.isImportDeclaration(node)) {
       formatter.hasLocalImports = true;
       extend(formatter.localImports, t.getBindingIdentifiers(node));
@@ -77,9 +77,9 @@ DefaultFormatter.prototype.getLocalImports = function () {
 };
 
 var remapVisitor = {
-  enter: function (node, parent, scope, context, formatter) {
+  enter: function (node, parent, scope, formatter) {
     if (t.isUpdateExpression(node) && formatter.isLocalReference(node.argument, scope)) {
-      context.skip();
+      this.skip();
 
       // expand to long file assignment expression
       var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));
@@ -107,7 +107,7 @@ var remapVisitor = {
     }
 
     if (t.isAssignmentExpression(node) && formatter.isLocalReference(node.left, scope)) {
-      context.skip();
+      this.skip();
       return formatter.remapExportAssignment(node);
     }
   }
diff --git a/lib/6to5/transformation/modules/system.js b/lib/6to5/transformation/modules/system.js
index 4f0f3f0208..0d333037d5 100644
--- a/lib/6to5/transformation/modules/system.js
+++ b/lib/6to5/transformation/modules/system.js
@@ -68,7 +68,7 @@ SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
 };
 
 var runnerSettersVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (node._importSource === state.source) {
       if (t.isVariableDeclaration(node)) {
         each(node.declarations, function (declar) {
@@ -81,7 +81,7 @@ var runnerSettersVisitor = {
         state.nodes.push(node);
       }
 
-      context.remove();
+      this.remove();
     }
   }
 };
@@ -103,10 +103,10 @@ SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators
 };
 
 var hoistVariablesVisitor = {
-  enter: function (node, parent, scope, context, hoistDeclarators) {
+  enter: function (node, parent, scope, hoistDeclarators) {
     if (t.isFunction(node)) {
       // nothing inside is accessible
-      return context.skip();
+      return this.skip();
     }
 
     if (t.isVariableDeclaration(node)) {
@@ -148,12 +148,12 @@ var hoistVariablesVisitor = {
 };
 
 var hoistFunctionsVisitor = {
-  enter: function (node, parent, scope, context, handlerBody) {
-    if (t.isFunction(node)) context.skip();
+  enter: function (node, parent, scope, handlerBody) {
+    if (t.isFunction(node)) this.skip();
 
     if (t.isFunctionDeclaration(node) || node._blockHoist) {
       handlerBody.push(node);
-      context.remove();
+      this.remove();
     }
   }
 };
diff --git a/lib/6to5/transformation/transformer-pass.js b/lib/6to5/transformation/transformer-pass.js
index 84ce74350a..9b16df92f2 100644
--- a/lib/6to5/transformation/transformer-pass.js
+++ b/lib/6to5/transformation/transformer-pass.js
@@ -15,17 +15,6 @@ function TransformerPass(file, transformer) {
   this.file        = file;
 }
 
-TransformerPass.prototype.astRun = function (key) {
-  if (!this.shouldRun) return;
-
-  var handlers = this.handlers;
-  var file = this.file;
-
-  if (handlers.ast && handlers.ast[key]) {
-    handlers.ast[key](file.ast, file);
-  }
-};
-
 TransformerPass.prototype.canRun = function () {
   var transformer = this.transformer;
 
@@ -64,31 +53,12 @@ TransformerPass.prototype.checkNode = function (node) {
   }
 };
 
-var transformVisitor = {
-  enter: function (node, parent, scope, context, state) {
-    var fns = state.handlers[node.type];
-    if (!fns) return;
-    return fns.enter(node, parent, scope, context, state.file, state.pass);
-  },
-
-  exit: function (node, parent, scope, context, state) {
-    var fns = state.handlers[node.type];
-    if (!fns) return;
-    return fns.exit(node, parent, scope, context, state.file, state.pass);
-  }
-};
-
 TransformerPass.prototype.transform = function () {
   if (!this.shouldRun) return;
 
   var file = this.file;
 
-  util.debug(file.opts.filename + ": Running transformer " + this.transformer.key);
+  file.debug("Running transformer " + this.transformer.key);
 
-  this.astRun("before");
-
-  var state = { file: file, handlers: this.handlers, pass: this };
-  file.scope.traverse(file.ast, transformVisitor, state);
-
-  this.astRun("after");
+  file.scope.traverse(file.ast, this.handlers, file);
 };
diff --git a/lib/6to5/transformation/transformer.js b/lib/6to5/transformation/transformer.js
index 2f94ff3f69..31bf351efb 100644
--- a/lib/6to5/transformation/transformer.js
+++ b/lib/6to5/transformation/transformer.js
@@ -6,6 +6,7 @@ var TransformerPass = require("./transformer-pass");
 var isFunction      = require("lodash/lang/isFunction");
 var traverse        = require("../traversal");
 var isObject        = require("lodash/lang/isObject");
+var clone           = require("../helpers/clone");
 var each            = require("lodash/collection/each");
 
 /**
@@ -15,13 +16,23 @@ var each            = require("lodash/collection/each");
  */
 
 function Transformer(key, transformer, opts) {
-  this.manipulateOptions = transformer.manipulateOptions;
-  this.check             = transformer.check;
+  transformer = clone(transformer);
 
-  this.experimental = !!transformer.experimental;
-  this.playground   = !!transformer.playground;
-  this.secondPass   = !!transformer.secondPass;
-  this.optional     = !!transformer.optional;
+  var take = function (key) {
+    var val = transformer[key];
+    delete transformer[key];
+    return val;
+  };
+
+  this.manipulateOptions = take("manipulateOptions");
+  this.check             = take("check");
+  this.post              = take("post");
+  this.pre               = take("pre");
+
+  this.experimental = !!take("experimental");
+  this.playground   = !!take("playground");
+  this.secondPass   = !!take("secondPass");
+  this.optional     = !!take("optional");
 
   this.handlers = this.normalize(transformer);
   this.opts     = opts || {};
diff --git a/lib/6to5/transformation/transformers/es6/block-scoping-tdz.js b/lib/6to5/transformation/transformers/es6/block-scoping-tdz.js
index fcb38ec11b..df09f17e01 100644
--- a/lib/6to5/transformation/transformers/es6/block-scoping-tdz.js
+++ b/lib/6to5/transformation/transformers/es6/block-scoping-tdz.js
@@ -3,7 +3,7 @@
 var t = require("../../../types");
 
 var visitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (!t.isReferencedIdentifier(node, parent)) return;
 
     var declared = state.letRefs[node.name];
@@ -36,7 +36,7 @@ exports.optional = true;
 
 exports.Loop =
 exports.Program =
-exports.BlockStatement = function (node, parent, scope, context, file) {
+exports.BlockStatement = function (node, parent, scope, file) {
   var letRefs = node._letReferences;
   if (!letRefs) return;
 
diff --git a/lib/6to5/transformation/transformers/es6/block-scoping.js b/lib/6to5/transformation/transformers/es6/block-scoping.js
index 2a6edc14fd..b52a39f8bc 100644
--- a/lib/6to5/transformation/transformers/es6/block-scoping.js
+++ b/lib/6to5/transformation/transformers/es6/block-scoping.js
@@ -43,7 +43,7 @@ exports.VariableDeclaration = function (node, parent) {
   isLet(node, parent);
 };
 
-exports.Loop = function (node, parent, scope, context, file) {
+exports.Loop = function (node, parent, scope, file) {
   var init = node.left || node.init;
   if (isLet(init, node)) {
     t.ensureBlock(node);
@@ -54,7 +54,7 @@ exports.Loop = function (node, parent, scope, context, file) {
 };
 
 exports.Program =
-exports.BlockStatement = function (block, parent, scope, context, file) {
+exports.BlockStatement = function (block, parent, scope, file) {
   if (!t.isLoop(parent)) {
     var blockScoping = new BlockScoping(false, block, parent, scope, file);
     blockScoping.run();
@@ -108,7 +108,7 @@ BlockScoping.prototype.run = function () {
   }
 };
 
-function replace(node, parent, scope, context, remaps) {
+function replace(node, parent, scope, remaps) {
   if (!t.isReferencedIdentifier(node, parent)) return;
 
   var remap = remaps[node.name];
@@ -120,7 +120,7 @@ function replace(node, parent, scope, context, remaps) {
   } else {
     // scope already has it's own binding that doesn't
     // match the one we have a stored replacement for
-    if (context) context.skip();
+    if (this) this.skip();
   }
 }
 
@@ -129,7 +129,7 @@ var replaceVisitor = {
 };
 
 function traverseReplace(node, parent, scope, remaps) {
-  replace(node, parent, scope, null, remaps);
+  replace(node, parent, scope, remaps);
   scope.traverse(node, replaceVisitor, remaps);
 }
 
@@ -225,7 +225,7 @@ BlockScoping.prototype.needsClosure = function () {
 };
 
 var letReferenceFunctionVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     // not a direct reference
     if (!t.isReferencedIdentifier(node, parent)) return;
 
@@ -241,10 +241,10 @@ var letReferenceFunctionVisitor = {
 };
 
 var letReferenceBlockVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isFunction(node)) {
       scope.traverse(node, letReferenceFunctionVisitor, state);
-      return context.skip();
+      return this.skip();
     }
   }
 };
@@ -310,7 +310,7 @@ var loopNodeTo = function (node) {
 };
 
 var loopVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     var replace;
 
     if (t.isLoop(node)) {
@@ -320,7 +320,7 @@ var loopVisitor = {
     }
 
     if (t.isFunction(node) || t.isLoop(node)) {
-      return context.skip();
+      return this.skip();
     }
 
     var loopText = loopNodeTo(node);
@@ -362,7 +362,7 @@ var loopVisitor = {
 };
 
 var loopLabelVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isLabeledStatement(node)) {
       state.innerLabels.push(node.label.name);
     }
@@ -395,7 +395,7 @@ BlockScoping.prototype.checkLoop = function () {
 };
 
 var hoistVarDeclarationsVisitor = {
-  enter: function (node, parent, scope, context, self) {
+  enter: function (node, parent, scope, self) {
     if (t.isForStatement(node)) {
       if (isVar(node.init, node)) {
         node.init = t.sequenceExpression(self.pushDeclar(node.init));
@@ -407,7 +407,7 @@ var hoistVarDeclarationsVisitor = {
     } else if (isVar(node, parent)) {
       return self.pushDeclar(node).map(t.expressionStatement);
     } else if (t.isFunction(node)) {
-      return context.skip();
+      return this.skip();
     }
   }
 };
diff --git a/lib/6to5/transformation/transformers/es6/classes.js b/lib/6to5/transformation/transformers/es6/classes.js
index d45297f4d9..9372e17c06 100644
--- a/lib/6to5/transformation/transformers/es6/classes.js
+++ b/lib/6to5/transformation/transformers/es6/classes.js
@@ -8,11 +8,11 @@ var t             = require("../../../types");
 
 exports.check = t.isClass;
 
-exports.ClassDeclaration = function (node, parent, scope, context, file) {
+exports.ClassDeclaration = function (node, parent, scope, file) {
   return new Class(node, file, scope, true).run();
 };
 
-exports.ClassExpression = function (node, parent, scope, context, file) {
+exports.ClassExpression = function (node, parent, scope, file) {
   if (!node.id) {
     if (t.isProperty(parent) && parent.value === node && !parent.computed && t.isIdentifier(parent.key)) {
       // var o = { foo: class {} };
diff --git a/lib/6to5/transformation/transformers/es6/constants.js b/lib/6to5/transformation/transformers/es6/constants.js
index d41de48b88..ce888a17bd 100644
--- a/lib/6to5/transformation/transformers/es6/constants.js
+++ b/lib/6to5/transformation/transformers/es6/constants.js
@@ -7,7 +7,7 @@ exports.check = function (node) {
 };
 
 var visitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isAssignmentExpression(node) || t.isUpdateExpression(node)) {
       var ids = t.getBindingIdentifiers(node);
 
@@ -30,12 +30,12 @@ var visitor = {
         throw state.file.errorWithNode(id, key + " is read-only");
       }
     } else if (t.isScope(node)) {
-      context.skip();
+      this.skip();
     }
   }
 };
 
-exports.Scope = function (node, parent, scope, context, file) {
+exports.Scope = function (node, parent, scope, file) {
   scope.traverse(node, visitor, {
     constants: scope.getAllDeclarationsOfKind("const"),
     file:      file
diff --git a/lib/6to5/transformation/transformers/es6/destructuring.js b/lib/6to5/transformation/transformers/es6/destructuring.js
index 9a08a475b3..7e26902dd3 100644
--- a/lib/6to5/transformation/transformers/es6/destructuring.js
+++ b/lib/6to5/transformation/transformers/es6/destructuring.js
@@ -178,7 +178,7 @@ Destructuring.prototype.init = function (pattern, parentId) {
 };
 
 exports.ForInStatement =
-exports.ForOfStatement = function (node, parent, scope, context, file) {
+exports.ForOfStatement = function (node, parent, scope, file) {
   var declar = node.left;
   if (!t.isVariableDeclaration(declar)) return;
 
@@ -207,7 +207,7 @@ exports.ForOfStatement = function (node, parent, scope, context, file) {
   block.body = nodes.concat(block.body);
 };
 
-exports.Function = function (node, parent, scope, context, file) {
+exports.Function = function (node, parent, scope, file) {
   var nodes = [];
 
   var hasDestructuring = false;
@@ -238,7 +238,7 @@ exports.Function = function (node, parent, scope, context, file) {
   block.body = nodes.concat(block.body);
 };
 
-exports.CatchClause = function (node, parent, scope, context, file) {
+exports.CatchClause = function (node, parent, scope, file) {
   var pattern = node.param;
   if (!t.isPattern(pattern)) return;
 
@@ -258,7 +258,7 @@ exports.CatchClause = function (node, parent, scope, context, file) {
   node.body.body = nodes.concat(node.body.body);
 };
 
-exports.ExpressionStatement = function (node, parent, scope, context, file) {
+exports.ExpressionStatement = function (node, parent, scope, file) {
   var expr = node.expression;
   if (expr.type !== "AssignmentExpression") return;
   if (!t.isPattern(expr.left)) return;
@@ -282,7 +282,7 @@ exports.ExpressionStatement = function (node, parent, scope, context, file) {
   return nodes;
 };
 
-exports.AssignmentExpression = function (node, parent, scope, context, file) {
+exports.AssignmentExpression = function (node, parent, scope, file) {
   if (!t.isPattern(node.left)) return;
 
   var ref = scope.generateUidIdentifier("temp");
@@ -316,7 +316,7 @@ var variableDeclarationhasPattern = function (node) {
   return false;
 };
 
-exports.VariableDeclaration = function (node, parent, scope, context, file) {
+exports.VariableDeclaration = function (node, parent, scope, file) {
   if (t.isForInStatement(parent) || t.isForOfStatement(parent)) return;
   if (!variableDeclarationhasPattern(node)) return;
 
diff --git a/lib/6to5/transformation/transformers/es6/for-of.js b/lib/6to5/transformation/transformers/es6/for-of.js
index 938ab0df42..85b01dd4bf 100644
--- a/lib/6to5/transformation/transformers/es6/for-of.js
+++ b/lib/6to5/transformation/transformers/es6/for-of.js
@@ -5,11 +5,11 @@ var t    = require("../../../types");
 
 exports.check = t.isForOfStatement;
 
-exports.ForOfStatement = function (node, parent, scope, context, file) {
+exports.ForOfStatement = function (node, parent, scope, file) {
   var callback = spec;
   if (file.isLoose("es6.forOf")) callback = loose;
 
-  var build  = callback(node, parent, scope, context, file);
+  var build  = callback(node, parent, scope, file);
   var declar = build.declar;
   var loop   = build.loop;
   var block  = loop.body;
@@ -34,7 +34,7 @@ exports.ForOfStatement = function (node, parent, scope, context, file) {
   return loop;
 };
 
-var loose = function (node, parent, scope, context, file) {
+var loose = function (node, parent, scope, file) {
   var left = node.left;
   var declar, id;
 
@@ -71,7 +71,7 @@ var loose = function (node, parent, scope, context, file) {
   };
 };
 
-var spec = function (node, parent, scope, context, file) {
+var spec = function (node, parent, scope, file) {
   var left = node.left;
   var declar;
 
diff --git a/lib/6to5/transformation/transformers/es6/modules.js b/lib/6to5/transformation/transformers/es6/modules.js
index 9249b3da64..23b8a106c2 100644
--- a/lib/6to5/transformation/transformers/es6/modules.js
+++ b/lib/6to5/transformation/transformers/es6/modules.js
@@ -4,7 +4,7 @@ var t = require("../../../types");
 
 exports.check = require("../internal/modules").check;
 
-exports.ImportDeclaration = function (node, parent, scope, context, file) {
+exports.ImportDeclaration = function (node, parent, scope, file) {
   var nodes = [];
 
   if (node.specifiers.length) {
@@ -23,7 +23,7 @@ exports.ImportDeclaration = function (node, parent, scope, context, file) {
   return nodes;
 };
 
-exports.ExportDeclaration = function (node, parent, scope, context, file) {
+exports.ExportDeclaration = function (node, parent, scope, file) {
   var nodes = [];
   var i;
 
diff --git a/lib/6to5/transformation/transformers/es6/parameters.default.js b/lib/6to5/transformation/transformers/es6/parameters.default.js
index 204e8fb46e..b56b6ee34f 100644
--- a/lib/6to5/transformation/transformers/es6/parameters.default.js
+++ b/lib/6to5/transformation/transformers/es6/parameters.default.js
@@ -15,10 +15,10 @@ var hasDefaults = function (node) {
 };
 
 var iifeVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isReferencedIdentifier(node, parent) && state.scope.hasOwnReference(node.name)) {
       state.iife = true;
-      context.stop();
+      this.stop();
     }
   }
 };
diff --git a/lib/6to5/transformation/transformers/es6/properties.computed.js b/lib/6to5/transformation/transformers/es6/properties.computed.js
index 1b557a6d35..194f30e663 100644
--- a/lib/6to5/transformation/transformers/es6/properties.computed.js
+++ b/lib/6to5/transformation/transformers/es6/properties.computed.js
@@ -6,7 +6,7 @@ exports.check = function (node) {
   return t.isProperty(node) && node.computed;
 };
 
-exports.ObjectExpression = function (node, parent, scope, context, file) {
+exports.ObjectExpression = function (node, parent, scope, file) {
   var hasComputed = false;
 
   for (var i = 0; i < node.properties.length; i++) {
diff --git a/lib/6to5/transformation/transformers/es6/properties.shorthand.js b/lib/6to5/transformation/transformers/es6/properties.shorthand.js
index 81fd7c40cb..fff70cef38 100644
--- a/lib/6to5/transformation/transformers/es6/properties.shorthand.js
+++ b/lib/6to5/transformation/transformers/es6/properties.shorthand.js
@@ -8,7 +8,7 @@ exports.check = function (node) {
   return t.isProperty(node) && (node.method || node.shorthand);
 };
 
-exports.Property = function (node, parent, scope, context, file) {
+exports.Property = function (node, parent, scope, file) {
   if (node.method) {
     node.method = false;
     nameMethod.property(node, file, scope);
diff --git a/lib/6to5/transformation/transformers/es6/spread.js b/lib/6to5/transformation/transformers/es6/spread.js
index 46ffecfcae..bea2ce9ee2 100644
--- a/lib/6to5/transformation/transformers/es6/spread.js
+++ b/lib/6to5/transformation/transformers/es6/spread.js
@@ -44,7 +44,7 @@ var build = function (props, file) {
   return nodes;
 };
 
-exports.ArrayExpression = function (node, parent, scope, context, file) {
+exports.ArrayExpression = function (node, parent, scope, file) {
   var elements = node.elements;
   if (!hasSpread(elements)) return;
 
@@ -59,7 +59,7 @@ exports.ArrayExpression = function (node, parent, scope, context, file) {
   return t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
 };
 
-exports.CallExpression = function (node, parent, scope, context, file) {
+exports.CallExpression = function (node, parent, scope, file) {
   var args = node.arguments;
   if (!hasSpread(args)) return;
 
@@ -99,7 +99,7 @@ exports.CallExpression = function (node, parent, scope, context, file) {
   node.arguments.unshift(contextLiteral);
 };
 
-exports.NewExpression = function (node, parent, scope, context, file) {
+exports.NewExpression = function (node, parent, scope, file) {
   var args = node.arguments;
   if (!hasSpread(args)) return;
 
diff --git a/lib/6to5/transformation/transformers/es6/template-literals.js b/lib/6to5/transformation/transformers/es6/template-literals.js
index 4fcb9243b3..7124c53401 100644
--- a/lib/6to5/transformation/transformers/es6/template-literals.js
+++ b/lib/6to5/transformation/transformers/es6/template-literals.js
@@ -10,7 +10,7 @@ exports.check = function (node) {
   return t.isTemplateLiteral(node) || t.isTaggedTemplateExpression(node);
 };
 
-exports.TaggedTemplateExpression = function (node, parent, scope, context, file) {
+exports.TaggedTemplateExpression = function (node, parent, scope, file) {
   var args = [];
   var quasi = node.quasi;
 
diff --git a/lib/6to5/transformation/transformers/es7/abstract-references.js b/lib/6to5/transformation/transformers/es7/abstract-references.js
index fa1ed60dfa..d86cbaa7fc 100644
--- a/lib/6to5/transformation/transformers/es7/abstract-references.js
+++ b/lib/6to5/transformation/transformers/es7/abstract-references.js
@@ -23,7 +23,7 @@ var container = function (parent, call, ret, file) {
   }
 };
 
-exports.AssignmentExpression = function (node, parent, scope, context, file) {
+exports.AssignmentExpression = function (node, parent, scope, file) {
   var left = node.left;
   if (!t.isVirtualPropertyExpression(left)) return;
 
@@ -63,7 +63,7 @@ exports.AssignmentExpression = function (node, parent, scope, context, file) {
   return container(parent, call, value, file);
 };
 
-exports.UnaryExpression = function (node, parent, scope, context, file) {
+exports.UnaryExpression = function (node, parent, scope, file) {
   var arg = node.argument;
   if (!t.isVirtualPropertyExpression(arg)) return;
   if (node.operator !== "delete") return;
diff --git a/lib/6to5/transformation/transformers/es7/comprehensions.js b/lib/6to5/transformation/transformers/es7/comprehensions.js
index a7b613ce69..98e7075d41 100644
--- a/lib/6to5/transformation/transformers/es7/comprehensions.js
+++ b/lib/6to5/transformation/transformers/es7/comprehensions.js
@@ -7,7 +7,7 @@ var t                  = require("../../../types");
 
 exports.experimental = true;
 
-exports.ComprehensionExpression = function (node, parent, scope, context, file) {
+exports.ComprehensionExpression = function (node, parent, scope, file) {
   var callback = array;
   if (node.generator) callback = generator;
   return callback(node, parent, scope, file);
diff --git a/lib/6to5/transformation/transformers/es7/object-rest-spread.js b/lib/6to5/transformation/transformers/es7/object-rest-spread.js
index f70d9572e7..9337b95871 100644
--- a/lib/6to5/transformation/transformers/es7/object-rest-spread.js
+++ b/lib/6to5/transformation/transformers/es7/object-rest-spread.js
@@ -19,7 +19,7 @@ var hasSpread = function (node) {
   return false;
 };
 
-exports.ObjectExpression = function (node, parent, scope, context, file) {
+exports.ObjectExpression = function (node, parent, scope, file) {
   if (!hasSpread(node)) return;
 
   var args = [];
diff --git a/lib/6to5/transformation/transformers/internal/alias-functions.js b/lib/6to5/transformation/transformers/internal/alias-functions.js
index 1290c17669..10f16d49d7 100644
--- a/lib/6to5/transformation/transformers/internal/alias-functions.js
+++ b/lib/6to5/transformation/transformers/internal/alias-functions.js
@@ -3,12 +3,12 @@
 var t = require("../../../types");
 
 var functionChildrenVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isFunction(node) && !node._aliasFunction) {
-      return context.skip();
+      return this.skip();
     }
 
-    if (node._ignoreAliasFunctions) return context.skip();
+    if (node._ignoreAliasFunctions) return this.skip();
 
     var getId;
 
@@ -25,11 +25,11 @@ var functionChildrenVisitor = {
 };
 
 var functionVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (!node._aliasFunction) {
       if (t.isFunction(node)) {
         // stop traversal of this node as it'll be hit again by this transformer
-        return context.skip();
+        return this.skip();
       } else {
         return;
       }
@@ -38,7 +38,7 @@ var functionVisitor = {
     // traverse all child nodes of this function and find `arguments` and `this`
     scope.traverse(node, functionChildrenVisitor, state);
 
-    return context.skip();
+    return this.skip();
   }
 };
 
diff --git a/lib/6to5/transformation/transformers/internal/module-formatter.js b/lib/6to5/transformation/transformers/internal/module-formatter.js
index 3bacf0a1dd..da60d60a4b 100644
--- a/lib/6to5/transformation/transformers/internal/module-formatter.js
+++ b/lib/6to5/transformation/transformers/internal/module-formatter.js
@@ -2,16 +2,16 @@
 
 var useStrict = require("../../helpers/use-strict");
 
-exports.Program = {
-  exit: function (program, parent, scope, context, file) {
-    if (!file.transformers["es6.modules"].canRun()) return;
+exports.post = function (file) {
+  if (!file.transformers["es6.modules"].canRun()) return;
 
-    useStrict.wrap(program, function () {
-      program.body = file.dynamicImports.concat(program.body);
-    });
+  var program = file.ast.program;
 
-    if (file.moduleFormatter.transform) {
-      file.moduleFormatter.transform(program);
-    }
+  useStrict.wrap(program, function () {
+    program.body = file.dynamicImports.concat(program.body);
+  });
+
+  if (file.moduleFormatter.transform) {
+    file.moduleFormatter.transform(program);
   }
 };
diff --git a/lib/6to5/transformation/transformers/internal/modules.js b/lib/6to5/transformation/transformers/internal/modules.js
index 5c0a82f2cc..fabf23c62a 100644
--- a/lib/6to5/transformation/transformers/internal/modules.js
+++ b/lib/6to5/transformation/transformers/internal/modules.js
@@ -8,7 +8,7 @@
 
 var t = require("../../../types");
 
-var resolveModuleSource = function (node, parent, scope, context, file) {
+var resolveModuleSource = function (node, parent, scope, file) {
   var resolveModuleSource = file.opts.resolveModuleSource;
   if (node.source && resolveModuleSource) {
     node.source.value = resolveModuleSource(node.source.value);
diff --git a/lib/6to5/transformation/transformers/minification/dead-code-elimination.js b/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
index 5668829823..b5ded93996 100644
--- a/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
+++ b/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
@@ -2,7 +2,7 @@ var t = require("../../../types");
 
 exports.optional = true;
 
-exports.ExpressionStatement = function (node, parent, scope, context) {
+exports.ExpressionStatement = function (node, parent, scope) {
   // remove consequenceless expressions such as local variables and literals
   //
   //   var foo = true; foo; -> var foo = true;
@@ -11,12 +11,12 @@ exports.ExpressionStatement = function (node, parent, scope, context) {
 
   var expr = node.expression;
   if (t.isLiteral(expr) || (t.isIdentifier(node) && t.hasBinding(node.name))) {
-    context.remove();
+    this.remove();
   }
 };
 
 exports.IfStatement = {
-  exit: function (node, parent, scope, context) {
+  exit: function (node, parent, scope) {
     // todo: in scenarios where we can just return the consequent or
     // alternate we should drop the block statement if it contains no
     // block scoped variables
@@ -47,7 +47,7 @@ exports.IfStatement = {
       if (alternate) {
         return alternate;
       } else {
-        return context.remove();
+        return this.remove();
       }
     }
 
diff --git a/lib/6to5/transformation/transformers/minification/remove-console-calls.js b/lib/6to5/transformation/transformers/minification/remove-console-calls.js
index 09ff326e15..bac1650af9 100644
--- a/lib/6to5/transformation/transformers/minification/remove-console-calls.js
+++ b/lib/6to5/transformation/transformers/minification/remove-console-calls.js
@@ -6,8 +6,8 @@ var isConsole = t.buildMatchMemberExpression("console", true);
 
 exports.optional = true;
 
-exports.CallExpression = function (node, parent, scope, context) {
+exports.CallExpression = function (node, parent, scope) {
   if (isConsole(node.callee)) {
-    context.remove();
+    this.remove();
   }
 };
diff --git a/lib/6to5/transformation/transformers/minification/remove-debugger.js b/lib/6to5/transformation/transformers/minification/remove-debugger.js
index 5df8930923..b8950c888a 100644
--- a/lib/6to5/transformation/transformers/minification/remove-debugger.js
+++ b/lib/6to5/transformation/transformers/minification/remove-debugger.js
@@ -2,8 +2,8 @@ var t = require("../../../types");
 
 exports.optional = true;
 
-exports.ExpressionStatement = function (node, parent, scope, context) {
+exports.ExpressionStatement = function (node, parent, scope) {
   if (t.isIdentifier(node.expression, { name: "debugger" })) {
-    context.remove();
+    this.remove();
   }
 };
diff --git a/lib/6to5/transformation/transformers/other/async-to-generator.js b/lib/6to5/transformation/transformers/other/async-to-generator.js
index 790078275a..a9085e887b 100644
--- a/lib/6to5/transformation/transformers/other/async-to-generator.js
+++ b/lib/6to5/transformation/transformers/other/async-to-generator.js
@@ -7,7 +7,7 @@ exports.optional = true;
 
 exports.manipulateOptions = bluebirdCoroutines.manipulateOptions;
 
-exports.Function = function (node, parent, scope, context, file) {
+exports.Function = function (node, parent, scope, file) {
   if (!node.async || node.generator) return;
 
   return remapAsyncToGenerator(node, file.addHelper("async-to-generator"), scope);
diff --git a/lib/6to5/transformation/transformers/other/bluebird-coroutines.js b/lib/6to5/transformation/transformers/other/bluebird-coroutines.js
index 4d51fdda16..b32a5f14bb 100644
--- a/lib/6to5/transformation/transformers/other/bluebird-coroutines.js
+++ b/lib/6to5/transformation/transformers/other/bluebird-coroutines.js
@@ -10,7 +10,7 @@ exports.manipulateOptions = function (opts) {
 
 exports.optional = true;
 
-exports.Function = function (node, parent, scope, context, file) {
+exports.Function = function (node, parent, scope, file) {
   if (!node.async || node.generator) return;
 
   return remapAsyncToGenerator(
diff --git a/lib/6to5/transformation/transformers/other/react.js b/lib/6to5/transformation/transformers/other/react.js
index e265fb7b1e..e20a4fc85d 100644
--- a/lib/6to5/transformation/transformers/other/react.js
+++ b/lib/6to5/transformation/transformers/other/react.js
@@ -26,7 +26,7 @@ exports.JSXIdentifier = function (node, parent) {
   }
 };
 
-exports.JSXNamespacedName = function (node, parent, scope, context, file) {
+exports.JSXNamespacedName = function (node, parent, scope, file) {
   throw file.errorWithNode(node, "Namespace tags are not supported. ReactJSX is not XML.");
 };
 
@@ -53,7 +53,7 @@ var isCompatTag = function (tagName) {
 };
 
 exports.JSXOpeningElement = {
-  exit: function (node, parent, scope, context, file) {
+  exit: function (node, parent, scope, file) {
     var reactCompat = file.opts.reactCompat;
     var tagExpr = node.name;
     var args = [];
@@ -259,7 +259,7 @@ var addDisplayName = function (id, call) {
   }
 };
 
-exports.ExportDeclaration = function (node, parent, scope, context, file) {
+exports.ExportDeclaration = function (node, parent, scope, file) {
   if (node.default && react.isCreateClass(node.declaration)) {
     addDisplayName(file.opts.basename, node.declaration);
   }
diff --git a/lib/6to5/transformation/transformers/other/regenerator.js b/lib/6to5/transformation/transformers/other/regenerator.js
index 766956e95d..2f2724d553 100644
--- a/lib/6to5/transformation/transformers/other/regenerator.js
+++ b/lib/6to5/transformation/transformers/other/regenerator.js
@@ -1,6 +1,7 @@
 "use strict";
 
 var regenerator = require("regenerator-6to5");
+var t           = require("../../../types");
 
 exports.check = function (node) {
   return t.isFunction(node) && (node.async || node.generator);
diff --git a/lib/6to5/transformation/transformers/other/self-contained.js b/lib/6to5/transformation/transformers/other/self-contained.js
index 3ff1c8d9da..5cfb06f95c 100644
--- a/lib/6to5/transformation/transformers/other/self-contained.js
+++ b/lib/6to5/transformation/transformers/other/self-contained.js
@@ -20,7 +20,7 @@ var ALIASABLE_CONSTRUCTORS = [
 ];
 
 var astVisitor = {
-  enter: function (node, parent, scope, context, file) {
+  enter: function (node, parent, scope, file) {
     var prop;
 
     if (t.isMemberExpression(node) && t.isReferenced(node, parent)) {
@@ -31,7 +31,7 @@ var astVisitor = {
       if (!t.isReferenced(obj, node)) return;
 
       if (!node.computed && coreHas(obj) && has(core[obj.name], prop.name) && !scope.getBinding(obj.name)) {
-        context.skip();
+        this.skip();
         return t.prependToMemberExpression(node, file.get("coreIdentifier"));
       }
     } else if (t.isReferencedIdentifier(node, parent) && !t.isMemberExpression(parent) && contains(ALIASABLE_CONSTRUCTORS, node.name) && !scope.getBinding(node.name)) {
@@ -64,27 +64,25 @@ exports.manipulateOptions = function (opts) {
   if (opts.whitelist.length) opts.whitelist.push("es6.modules");
 };
 
-exports.Program = {
-  enter: function (node, parent, scope, context, file) {
-    file.setDynamic("runtimeIdentifier", function () {
-      return file.addImport("6to5-runtime/helpers", "to5Helpers");
-    });
-
-    file.setDynamic("coreIdentifier", function () {
-      return file.addImport("6to5-runtime/core-js", "core");
-    });
-
-    file.setDynamic("regeneratorIdentifier", function () {
-      return file.addImport("6to5-runtime/regenerator", "regeneratorRuntime");
-    });
-  },
-
-  exit: function (node, parent, scope, context, file) {
-    file.scope.traverse(node, astVisitor, file);
-  }
+exports.post = function (file) {
+  file.scope.traverse(file.ast, astVisitor, file);
 };
 
-exports.Identifier = function (node, parent, scope, context, file) {
+exports.pre = function ( file) {
+  file.setDynamic("runtimeIdentifier", function () {
+    return file.addImport("6to5-runtime/helpers", "to5Helpers");
+  });
+
+  file.setDynamic("coreIdentifier", function () {
+    return file.addImport("6to5-runtime/core-js", "core");
+  });
+
+  file.setDynamic("regeneratorIdentifier", function () {
+    return file.addImport("6to5-runtime/regenerator", "regeneratorRuntime");
+  });
+};
+
+exports.Identifier = function (node, parent, scope, file) {
   if (node.name === "regeneratorRuntime" && t.isReferenced(node, parent)) {
     return file.get("regeneratorIdentifier");
   }
diff --git a/lib/6to5/transformation/transformers/other/use-strict.js b/lib/6to5/transformation/transformers/other/use-strict.js
index 87d9672cc8..3a7db8257e 100644
--- a/lib/6to5/transformation/transformers/other/use-strict.js
+++ b/lib/6to5/transformation/transformers/other/use-strict.js
@@ -3,17 +3,16 @@
 var useStrict = require("../../helpers/use-strict");
 var t         = require("../../../types");
 
-exports.Program = {
-  exit: function (program) {
-    if (!useStrict.has(program)) {
-      program.body.unshift(t.expressionStatement(t.literal("use strict")));
-    }
+exports.post = function (file) {
+  var program = file.ast.program;
+  if (!useStrict.has(program)) {
+    program.body.unshift(t.expressionStatement(t.literal("use strict")));
   }
 };
 
 exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, scope, context) {
-  context.skip();
+exports.FunctionExpression = function (node, parent, scope) {
+  this.skip();
 };
 
 exports.ThisExpression = function () {
diff --git a/lib/6to5/transformation/transformers/playground/method-binding.js b/lib/6to5/transformation/transformers/playground/method-binding.js
index 47e08b86ef..085496a46b 100644
--- a/lib/6to5/transformation/transformers/playground/method-binding.js
+++ b/lib/6to5/transformation/transformers/playground/method-binding.js
@@ -26,7 +26,7 @@ exports.BindMemberExpression = function (node, parent, scope) {
   }
 };
 
-exports.BindFunctionExpression = function (node, parent, scope, context, file) {
+exports.BindFunctionExpression = function (node, parent, scope, file) {
   var buildCall = function (args) {
     var param = scope.generateUidIdentifier("val");
     return t.functionExpression(null, [param], t.blockStatement([
diff --git a/lib/6to5/transformation/transformers/playground/object-getter-memoization.js b/lib/6to5/transformation/transformers/playground/object-getter-memoization.js
index 5f49b46dc2..7ceaee2943 100644
--- a/lib/6to5/transformation/transformers/playground/object-getter-memoization.js
+++ b/lib/6to5/transformation/transformers/playground/object-getter-memoization.js
@@ -5,8 +5,8 @@ var t = require("../../../types");
 exports.playground = true;
 
 var visitor = {
-  enter: function (node, parent, scope, context, state) {
-    if (t.isFunction(node)) return context.skip();
+  enter: function (node, parent, scope, state) {
+    if (t.isFunction(node)) return this.skip();
 
     if (t.isReturnStatement(node) && node.argument) {
       node.argument = t.memberExpression(t.callExpression(state.file.addHelper("define-property"), [
@@ -19,7 +19,7 @@ var visitor = {
 };
 
 exports.Property =
-exports.MethodDefinition = function (node, parent, scope, context, file) {
+exports.MethodDefinition = function (node, parent, scope, file) {
   if (node.kind !== "memo") return;
   node.kind = "get";
 
diff --git a/lib/6to5/transformation/transformers/spec/proto-to-assign.js b/lib/6to5/transformation/transformers/spec/proto-to-assign.js
index e63e03696c..dac84dfecc 100644
--- a/lib/6to5/transformation/transformers/spec/proto-to-assign.js
+++ b/lib/6to5/transformation/transformers/spec/proto-to-assign.js
@@ -19,7 +19,7 @@ var buildDefaultsCallExpression = function (expr, ref, file) {
 exports.optional = true;
 exports.secondPass = true;
 
-exports.AssignmentExpression = function (node, parent, scope, context, file) {
+exports.AssignmentExpression = function (node, parent, scope, file) {
   if (!isProtoAssignmentExpression(node)) return;
 
   var nodes = [];
@@ -33,7 +33,7 @@ exports.AssignmentExpression = function (node, parent, scope, context, file) {
   return t.toSequenceExpression(nodes);
 };
 
-exports.ExpressionStatement = function (node, parent, scope, context, file) {
+exports.ExpressionStatement = function (node, parent, scope, file) {
   var expr = node.expression;
   if (!t.isAssignmentExpression(expr, { operator: "=" })) return;
 
@@ -42,7 +42,7 @@ exports.ExpressionStatement = function (node, parent, scope, context, file) {
   }
 };
 
-exports.ObjectExpression = function (node, parent, scope, context, file) {
+exports.ObjectExpression = function (node, parent, scope, file) {
   var proto;
 
   for (var i = 0; i < node.properties.length; i++) {
diff --git a/lib/6to5/transformation/transformers/spec/typeof-symbol.js b/lib/6to5/transformation/transformers/spec/typeof-symbol.js
index c4a10c6fa1..ce3e6016b5 100644
--- a/lib/6to5/transformation/transformers/spec/typeof-symbol.js
+++ b/lib/6to5/transformation/transformers/spec/typeof-symbol.js
@@ -4,8 +4,8 @@ var t = require("../../../types");
 
 exports.optional = true;
 
-exports.UnaryExpression = function (node, parent, scope, context, file) {
-  context.skip();
+exports.UnaryExpression = function (node, parent, scope, file) {
+  this.skip();
 
   if (node.operator === "typeof") {
     var call = t.callExpression(file.addHelper("typeof"), [node.argument]);
diff --git a/lib/6to5/transformation/transformers/validation/no-for-in-of-assignment.js b/lib/6to5/transformation/transformers/validation/no-for-in-of-assignment.js
index 165b888533..e00e74d8ab 100644
--- a/lib/6to5/transformation/transformers/validation/no-for-in-of-assignment.js
+++ b/lib/6to5/transformation/transformers/validation/no-for-in-of-assignment.js
@@ -3,7 +3,7 @@
 var t = require("../../../types");
 
 exports.ForInStatement =
-exports.ForOfStatement = function (node, parent, scope, context, file) {
+exports.ForOfStatement = function (node, parent, scope, file) {
   var left = node.left;
   if (t.isVariableDeclaration(left)) {
     var declar = left.declarations[0];
diff --git a/lib/6to5/transformation/transformers/validation/setters.js b/lib/6to5/transformation/transformers/validation/setters.js
index e104022bbc..bb4e7e1ab8 100644
--- a/lib/6to5/transformation/transformers/validation/setters.js
+++ b/lib/6to5/transformation/transformers/validation/setters.js
@@ -1,7 +1,7 @@
 "use strict";
 
 exports.MethodDefinition =
-exports.Property = function (node, parent, scope, context, file) {
+exports.Property = function (node, parent, scope, file) {
   if (node.kind === "set" && node.value.params.length !== 1) {
     throw file.errorWithNode(node.value, "Setters must have only one parameter");
   }
diff --git a/lib/6to5/transformation/transformers/validation/undeclared-variable-check.js b/lib/6to5/transformation/transformers/validation/undeclared-variable-check.js
index 919d417f2f..ebf66d15fc 100644
--- a/lib/6to5/transformation/transformers/validation/undeclared-variable-check.js
+++ b/lib/6to5/transformation/transformers/validation/undeclared-variable-check.js
@@ -5,7 +5,7 @@ var t           = require("../../../types");
 
 exports.optional = true;
 
-exports.Identifier = function (node, parent, scope, context, file) {
+exports.Identifier = function (node, parent, scope, file) {
   if (!t.isReferenced(node, parent)) return;
   if (scope.hasBinding(node.name)) return;
 
diff --git a/lib/6to5/traversal/context.js b/lib/6to5/traversal/context.js
index 995e7f6475..43db07f7a2 100644
--- a/lib/6to5/traversal/context.js
+++ b/lib/6to5/traversal/context.js
@@ -4,9 +4,9 @@
 
 module.exports = TraversalContext;
 
-var TraversalIteration = require("./iteration");
-var flatten            = require("lodash/array/flatten");
-var compact            = require("lodash/array/compact");
+var TraversalPath = require("./path");
+var flatten       = require("lodash/array/flatten");
+var compact       = require("lodash/array/compact");
 
 function TraversalContext(scope, opts, state) {
   this.shouldFlatten = false;
@@ -44,7 +44,7 @@ TraversalContext.prototype.reset = function () {
 
 TraversalContext.prototype.visitNode = function (node, obj, key) {
   this.reset();
-  var iteration = new TraversalIteration(this, node, obj, key);
+  var iteration = new TraversalPath(this, node, obj, key);
   return iteration.visit();
 };
 
diff --git a/lib/6to5/traversal/index.js b/lib/6to5/traversal/index.js
index b5f475d78f..8ebb8fbcd5 100644
--- a/lib/6to5/traversal/index.js
+++ b/lib/6to5/traversal/index.js
@@ -93,7 +93,7 @@ traverse.explode = function (obj) {
   return obj;
 };
 
-function hasBlacklistedType(node, parent, scope, context, state) {
+function hasBlacklistedType(node, parent, scope, state) {
   if (node.type === state.type) {
     state.has = true;
     context.skip();
diff --git a/lib/6to5/traversal/iteration.js b/lib/6to5/traversal/path.js
similarity index 56%
rename from lib/6to5/traversal/iteration.js
rename to lib/6to5/traversal/path.js
index 884cec41c8..19cac99043 100644
--- a/lib/6to5/traversal/iteration.js
+++ b/lib/6to5/traversal/path.js
@@ -1,6 +1,6 @@
 "use strict";
 
-module.exports = TraversalIteration;
+module.exports = TraversalPath;
 
 /* jshint maxparams:7 */
 
@@ -9,16 +9,42 @@ var contains = require("lodash/collection/contains");
 var Scope    = require("./scope");
 var t        = require("../types");
 
-function TraversalIteration(context, parent, obj, key) {
+function TraversalPath(context, parent, obj, key) {
+  this.shouldRemove = false;
+  this.shouldSkip   = false;
+  this.shouldStop   = false;
+
+  this.context = context;
+  this.state   = this.context.state;
+  this.opts    = this.context.opts;
+
   this.key     = key;
   this.obj     = obj;
-  this.context = context;
+
   this.parent  = parent;
-  this.scope   = TraversalIteration.getScope(this.getNode(), parent, context.scope);
+  this.scope   = TraversalPath.getScope(this.getNode(), parent, context.scope);
   this.state   = context.state;
 }
 
-TraversalIteration.getScope = function (node, parent, scope) {
+TraversalPath.prototype.remove = function () {
+  this.shouldRemove = true;
+  this.shouldSkip   = true;
+};
+
+TraversalPath.prototype.skip = function () {
+  this.shouldSkip = true;
+};
+
+TraversalPath.prototype.stop = function () {
+  this.shouldStop = true;
+  this.shouldSkip = true;
+};
+
+TraversalPath.prototype.flatten = function () {
+  this.context.flatten();
+};
+
+TraversalPath.getScope = function (node, parent, scope) {
   var ourScope = scope;
 
   // we're entering a new scope so let's construct it!
@@ -29,22 +55,22 @@ TraversalIteration.getScope = function (node, parent, scope) {
   return ourScope;
 };
 
-TraversalIteration.prototype.maybeRemove = function () {
-  if (this.context.shouldRemove) {
+TraversalPath.prototype.maybeRemove = function () {
+  if (this.shouldRemove) {
     this.setNode(null);
-    this.context.flatten();
+    this.flatten();
   }
 };
 
-TraversalIteration.prototype.setNode = function (val) {
+TraversalPath.prototype.setNode = function (val) {
   return this.obj[this.key] = val;
 };
 
-TraversalIteration.prototype.getNode = function () {
+TraversalPath.prototype.getNode = function () {
   return this.obj[this.key];
 };
 
-TraversalIteration.prototype.replaceNode = function (replacement, scope) {
+TraversalPath.prototype.replaceNode = function (replacement, scope) {
   var isArray = Array.isArray(replacement);
 
   // inherit comments from original node to the first replacement node
@@ -73,13 +99,19 @@ TraversalIteration.prototype.replaceNode = function (replacement, scope) {
       t.ensureBlock(this.obj, this.key);
     }
 
-    this.context.flatten();
+    this.flatten();
   }
 };
 
-TraversalIteration.prototype.call = function (fn) {
+TraversalPath.prototype.call = function (key) {
   var node = this.getNode();
-  var replacement = fn.call(this, node, this.parent, this.scope, this.context, this.state);
+  if (!node) return;
+
+  var opts = this.opts;
+  var fn   = opts[key];
+  if (opts[node.type]) fn = opts[node.type][key] || fn;
+
+  var replacement = fn.call(this, node, this.parent, this.scope, this.state);
 
   if (replacement) {
     this.replaceNode(replacement);
@@ -91,22 +123,19 @@ TraversalIteration.prototype.call = function (fn) {
   return node;
 };
 
-TraversalIteration.prototype.visit = function () {
-  this.context.reset();
-
-  var state = this.context.state;
-  var opts  = this.context.opts;
-  var node  = this.getNode();
+TraversalPath.prototype.visit = function () {
+  var opts = this.opts;
+  var node = this.getNode();
 
   // type is blacklisted
   if (opts.blacklist && opts.blacklist.indexOf(node.type) > -1) {
     return;
   }
 
-  this.call(opts.enter);
+  this.call("enter");
 
-  if (this.context.shouldSkip) {
-    return this.context.shouldStop;
+  if (this.shouldSkip) {
+    return this.shouldStop;
   }
 
   node = this.getNode();
@@ -115,12 +144,12 @@ TraversalIteration.prototype.visit = function () {
     // traverse over these replacement nodes we purposely don't call exitNode
     // as the original node has been destroyed
     for (var i = 0; i < node.length; i++) {
-      traverse.node(node[i], opts, this.scope, state);
+      traverse.node(node[i], opts, this.scope, this.state);
     }
   } else {
-    traverse.node(node, opts, this.scope, state);
-    this.call(opts.exit);
+    traverse.node(node, opts, this.scope, this.state);
+    this.call("exit");
   }
 
-  return this.context.shouldStop;
+  return this.shouldStop;
 };
diff --git a/lib/6to5/traversal/scope.js b/lib/6to5/traversal/scope.js
index 064aae2290..f752081409 100644
--- a/lib/6to5/traversal/scope.js
+++ b/lib/6to5/traversal/scope.js
@@ -213,7 +213,7 @@ Scope.prototype.registerVariableDeclaration = function (declar) {
 };
 
 var functionVariableVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isFor(node)) {
       each(t.FOR_INIT_KEYS, function (key) {
         var declar = node[key];
@@ -223,7 +223,7 @@ var functionVariableVisitor = {
 
     // this block is a function so we'll stop since none of the variables
     // declared within are accessible
-    if (t.isFunction(node)) return context.skip();
+    if (t.isFunction(node)) return this.skip();
 
     // function identifier doesn't belong to this scope
     if (state.blockId && node === state.blockId) return;
@@ -240,7 +240,7 @@ var functionVariableVisitor = {
 };
 
 var programReferenceVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isReferencedIdentifier(node, parent) && !scope.hasReference(node.name)) {
       state.register(node, true);
     }
@@ -248,11 +248,11 @@ var programReferenceVisitor = {
 };
 
 var blockVariableVisitor = {
-  enter: function (node, parent, scope, context, state) {
+  enter: function (node, parent, scope, state) {
     if (t.isBlockScoped(node)) {
       state.register(node);
     } else if (t.isScope(node)) {
-      context.skip();
+      this.skip();
     }
   }
 };
@@ -339,12 +339,6 @@ Scope.prototype.crawl = function () {
     });
   }
 
-  if (t.isFunctionExpression(block) && block.id) {
-    if (!t.isProperty(this.parentBlock, { method: true })) {
-      this.register(block.id);
-    }
-  }
-
   // Program
 
   if (t.isProgram(block)) {
diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index b9be071c03..501315617f 100644
--- a/lib/6to5/util.js
+++ b/lib/6to5/util.js
@@ -79,7 +79,7 @@ exports.sourceMapToComment = function (map) {
 };
 
 var templateVisitor = {
-  enter: function (node, parent, scope, context, nodes) {
+  enter: function (node, parent, scope, nodes) {
     if (t.isIdentifier(node) && has(nodes, node.name)) {
       return nodes[node.name];
     }
diff --git a/test/fixtures/transformation/self-contained/full/expected.js b/test/fixtures/transformation/self-contained/full/expected.js
index 2d01238c30..6e3064b562 100644
--- a/test/fixtures/transformation/self-contained/full/expected.js
+++ b/test/fixtures/transformation/self-contained/full/expected.js
@@ -2,10 +2,10 @@
 
 var _regeneratorRuntime = require("6to5-runtime/regenerator");
 
-var _core = require("6to5-runtime/core-js");
-
 var _to5Helpers = require("6to5-runtime/helpers");
 
+var _core = require("6to5-runtime/core-js");
+
 var giveWord = _regeneratorRuntime.mark(function giveWord() {
   return _regeneratorRuntime.wrap(function giveWord$(context$1$0) {
     while (1) switch (context$1$0.prev = context$1$0.next) {