(PHP 5 >= 5.3.0, PHP 7, PHP 8)
RecursiveTreeIterator::key — Get the key of the current element
Gets the current key prefixed and postfixed.
本函數還未編寫(xiě)文檔，僅有參數列表。
此函數沒(méi)有參數。
Returns the current key prefixed and postfixed.