@ SuppressWarnings ( "unchecked" ) private Zipper < K , V > compareDepth ( Tree < K , V > left , Tree < K , V > right ) { return unzipBoth ( left , right , ( List < Tree < K , V > > ) Collections . EMPTY_LIST , ( List < Tree < K , V > > ) Collections . EMPTY_LIST , 0 ) ; }
If the trees were balanced returns an empty zipper