anchor.diff:    }
   
     V _get(K key, int hash, int depth) {
  -    int branch = (hash >> (depth * 5)) & 0x1f;
  +    int branch = (hash >> (depth * branchingBits)) & branchingMask;
       int mask = 1 << branch;
       if ((_bitmap & mask) != 0) {
         int index = _popcount(_bitmap & (mask - 1));
  
positive.code: 
  
    _Node<K, V> _delete(owner, K key, int hash, int depth, bool missingOk) {
      int branch = (hash >> (depth * 5)) & 0x1f;
      int mask = 1 << branch;
  
      if ((_bitmap & mask) != 0) {
  
negative.code:       _insert(nkv, kv);
      }
  
  
      var a = polish(owner, depth, nkv);
      return a;
        // to meassure how long does polish take
  //    var a = polish(owner, depth, new List.from(nkv));
  //    var b = polish(owner, depth, new List.from(nkv));
  //    return _random.nextBool()?a:b;
    }
  
    _Node<K, V> _delete(_Owner owner, K key, int hash, int depth, bool missingOk) {
  