hunk.code_window: // Mixin subclasses
   mixin(KeyedSeq, KeyedCollection.prototype);
   mixin(IndexedSeq, IndexedCollection.prototype);
   mixin(SetSeq, SetCollection.prototype);
   // #pragma Helper functions
   function reduce(collection, reducer, reduction, context, useFirst, reverse) {
     assertNotInfinite(collection.size);
  
hunk.labels: keep keep keep replace replace replace keep keep keep keep keep
hunk.after_edit: mixin(KeyedSeq, KeyedCollectionPrototype);
   mixin(IndexedSeq, IndexedCollectionPrototype);
   mixin(SetSeq, SetCollectionPrototype);
  
hunk.file_path: src/CollectionImpl.js
hunk.type: replace
file: {
    "env": {
      "jest": true
    },
    "parserOptions": {
      "ecmaVersion": 6
    }
  }
  