pred.successorInValueSet = succ;
      }
      if (succ == null) {
        lastEntry = pred;
      } else {
        succ.predecessorInValueSet = pred;
      }
    }

    private void deleteFromValueSet(ValueEntry<K, V> entry) {
      succeedsInValueSet(entry.predecessorInValueSet, entry.successorInValueSet);
    }

    private void appendToValueSet(ValueEntry<K, V> newEntry) {