public function sortKeys( int $options = SORT_REGULAR, bool $desc = false )
	{
		$items = $this->items;
		$desc ? krsort($items, $options) : ksort($items, $options);
		return new static($items);
	}
public function sortKeys( int $options = SORT_REGULAR, bool $desc = false )
	{
		$items = $this->items;
		$desc ? krsort($items, $options) : ksort($items, $options);
		return new static($items);
	}
public function sortKeys ( int $ options = SORT_REGULAR , bool $ desc = false ) { $ items = $ this -> items ; $ desc ? krsort ( $ items , $ options ) : ksort ( $ items , $ options ) ; return new static ( $ items ) ; }
Sort an collection by key

@param int $options Sorting type flags
@param bool $desc In reverse order
@return static
Sort an collection by key