code: public function sortBy(callable $iteratee, $order = SORT_ASC, $preserveKeys = false)
      {
          return $this->sortWith($this->iterateeToComparator($iteratee, $order === SORT_ASC), $preserveKeys);
      }
docs: Returns a bag with the values sorted based on the `$iteratee` function.
  
  Example:
  
  $bag = Bag::from([
  ['name' => 'Bob'],
  ['name' => 'Alice'],
  ]);
  
  // Sort values by "name" property
  $bag->sortBy(function ($item) {
  return $item['name'];
  });
  // => Bag of [
  //     ['name' => 'Alice']
  //     ['name' => 'Bob']
  // ]
  
  @param callable $iteratee     Function given `($value)`
  @param int      $order        `SORT_ASC` or `SORT_DESC`
  @param bool     $preserveKeys Whether to preserve keys for maps or to re-index for lists
  
  @return static