code: function reduce(array, callback) {
      var accumulator = null;
      each(array, function(value, index) {
        accumulator = callback(accumulator, value, index, array);
      });
      return accumulator;
    }
docs: A bare-bones `Array#reduce` like utility function.
  
  @private
  @param {Array} array The array to iterate over.
  @param {Function} callback The function called per iteration.
  @returns {*} The accumulated result.