code: function arrayAggregator(array, setter, iteratee, accumulator) {
    var index = -1,
        length = array ? array.length : 0;
  
    while (++index < length) {
      var value = array[index];
      setter(accumulator, value, iteratee(value), array);
    }
    return accumulator;
  }
docs: A specialized version of `baseAggregator` for arrays.
  
  @private
  @param {Array} [array] The array to iterate over.
  @param {Function} setter The function to set `accumulator` values.
  @param {Function} iteratee The iteratee to transform keys.
  @param {Object} accumulator The initial aggregated object.
  @returns {Function} Returns `accumulator`.