text: const $array = require('./dist/dollar-array.js').$array;
  
  var key = 'lastname',
  filterByProp,
  simple,
  exampleArray = [
  	{ "name": "Juan", "lastname": "Perez", "user_id":"1234", "age": 42 },
  	{ "name": "John", "lastname": "Doe", "user_id":"6789", "age": 40 },
  	{ "name": "Pedro", "lastname": "Algo", age: 30 }
  ],
  array = $array(exampleArray);
  
  function log(word, arr){
    console.log(`${ word }: \n--------------\n\n${ JSON.stringify(arr, null, 2) } \n\n`)
  }
  
  
  log(`key`, key);
  log(`exampleArrayl`, exampleArray);
  log(`propExists("${key}")`, array.propExists(key));
  log(`filterByProp("${key}")`, array.filterByProp(key));
  log(`invert()`, array.invert(true));
  log(`ascend("${key}")`, array.ascend(key, true));
  log(`descend("${key}")`, array.descend(key, true));
  log(`randomize()`, array.randomize(true));
  log(`random()`, array.random());
  log(`toObject("${key}")`, array.toObject(key));
  log(`group([])`, array.group([
    o => o[key][0] === 'A',
    o => o[key][0] === 'P'
  ]));
  log(`group({})`, array.group({
    A: o => o[key][0] === 'A',
    P: o => o[key][0] === 'P'
  }));
  