sipadu_mbip/node_modules/collect.js/dist/methods/countBy.js

'use strict';

module.exports = function countBy() {
  var fn = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : function (value) {
    return value;
  };

  return new this.constructor(this.items).groupBy(fn).map(function (value) {
    return value.count();
  });
};