anchor.diff:      Nodes1 = lists:foldl(fun(I, Acc) ->
           {NodeId, {NodeMbr, NodeMeta, NodeData}} =
               vtree_test:random_node({I,27+I*329,45}),
  -        Node = {NodeMbr, NodeMeta, {NodeId, NodeData}},
  +        Node = {NodeMbr, NodeMeta, {[NodeId, <<"bulk">>], NodeData}},
           [Node|Acc]
       end, [], lists:seq(1,20)),
   
  
positive.code:     % Return new nodes (might be several ones)
      NewChildrenMbrAndPos.
  
  % XXX vmx: rename to _test when it should be run again
  seedtree_write_case1() ->
      % Test "Case 1: input R-tree fits in the target node" (chapter 6.1)
  
negative.code: 
  %%%%% Helpers %%%%%
  
  % @doc Returns the ceiling of log_N(X). Returns 1 for X==1.
  -spec log_n_ceil(N::integer(), X::integer()) -> integer().
  log_n_ceil(N, 1) ->
      1;
  log_n_ceil(N, X) ->
      ceiling(math:log(X) / math:log(N)).
  
  