anchor.diff:  
   insert(Leafs, RStar = {?MODULE, Params, Root0}) ->
       Root = insert_bulk(Leafs, Root0, Params),
  +    update_root(RStar, Root, Params).
  +
  +%%
  +
  +-spec remove(erstar_bound:bound(), any(), rtree()) -> rtree().
  +
  +remove(Bound, Data, RStar = {?MODULE, Params, Root0}) ->
  +    {[Root], Orphans} = remove_leaf(newleaf(Bound, Data), Root0, true, {[], []}, Params),
  +    FinalRoot = insert_bulk(Orphans, Root, Params),
  +    update_root(RStar, FinalRoot, Params).
  +
  +-spec remove([treeleaf()], rtree()) -> rtree().
  +
  +remove(Leaves, RStar = {?MODULE, Params, Root0}) ->
  +    Root = remove_bulk(Leaves, Root0, [], Params),
       update_root(RStar, Root, Params).
   
   %%
  
positive.code: 
  %%
  
  fold_deep(_Fun, Acc, _Level, []) ->
      Acc;
  
  
negative.code:     instance/1,
      insert/3,
      insert/2,
      remove/3,
      remove/2,
      fold/3,
      foldwide/3,
      walk/2,
  