question: Node < K , V > findLast ( ) { Index < K , V > q = head ; for ( ; ; ) { Index < K , V > d , r ; if ( ( r = q . right ) != null ) { if ( r . indexesDeletedNode ( ) ) { q . unlink ( r ) ; q = head ; } else q = r ; } else if ( ( d = q . down ) != null ) { q = d ; } else { Node < K , V > b = q . node ; Node < K , V > n = b . next ; for ( ; ; ) { if ( n == null ) return b . isBaseHeader ( ) ? null : b ; Node < K , V > f = n . next ; if ( n != b . next ) break ; Object v = n . value ; if ( v == null ) { n . helpDelete ( b , f ) ; break ; } if ( v == n || b . value == null ) break ; b = n ; n = f ; } q = head ; } } }
target:  Specialized version of find to get last valid node.