public function sortBy( \Closure $callback, bool $save_keys = true )
	{
		$items = $this->items;
		$save_keys ? uasort($items, $callback) : usort($items, $callback);
		return new static($items);
	}
public function sortBy( \Closure $callback, bool $save_keys = true )
	{
		$items = $this->items;
		$save_keys ? uasort($items, $callback) : usort($items, $callback);
		return new static($items);
	}
public function sortBy ( \ Closure $ callback , bool $ save_keys = true ) { $ items = $ this -> items ; $ save_keys ? uasort ( $ items , $ callback ) : usort ( $ items , $ callback ) ; return new static ( $ items ) ; }
Sort an collection by values using a user-defined comparison function

@param \Closure $callback
@param bool $save_keys maintain index association
@return static
Sort an collection by values using a user - defined comparison function