Function reduce

src/CollectionImpl.js:236–245

(reducer, initialReduction, context)

  },

  reduce(reducer, initialReduction, context) {
    return reduce(
      this,
      reducer,
      initialReduction,
      context,
      arguments.length < 2,
      false
    );
  },

  reduceRight(reducer, initialReduction, context) {
    return reduce(