question: private void clearIndexToFirst ( ) { for ( ; ; ) { Index < K , V > q = head ; for ( ; ; ) { Index < K , V > r = q . right ; if ( r != null && r . indexesDeletedNode ( ) && ! q . unlink ( r ) ) break ; if ( ( q = q . down ) == null ) { if ( head . right == null ) tryReduceLevel ( ) ; return ; } } } }
target:  Clears out index nodes associated with deleted first entry.