code: function each(list, fn) {
    var len = list ? list.length : 0;
    var i = 0;
    for (; i < len; ++i) {
      fn(list[i], i);
    }
    return list
  }
docs: Specialized function for looping an array-like collection with `each={}`
  @param   { Array } list - collection of items
  @param   {Function} fn - callback function
  @returns { Array } the array looped