code: function map(array, fn) {
  	const result = [];
  	let length = array.length;
  	while (length--) {
  		result[length] = fn(array[length]);
  	}
  	return result;
  }
docs: A generic `Array#map` utility function.
  @private
  @param {Array} array The array to iterate over.
  @param {Function} callback The function that gets called for every array
  item.
  @returns {Array} A new array of values returned by the callback function.