anchor.diff:                  {ok, LeftValue} -> mergeTrees(LeftValue, Value)
           end,
           hashMerge(maps:put(Key, NewValue, Left), Rest).
  +
  +compactNode(Node) when is_map(Node) ->
  +        maps:from_list([ {K, V} || {K, V} <- maps:to_list(Node), V =/= {#{}, []}]).
  
positive.code:         windex_db:store(primary_tree, Index, NewTree).
  
  delete(Index, Rev) -> ok.
  
  export({SubTree, Data}) when is_map(SubTree)->
          #{
  
negative.code: 
  makeTree(Revision) when is_map(Revision) -> {doMakeTree(Revision), []}.
  doMakeTree(Revision) when is_map(Revision) ->
          compactNode(maps:map(fun(_Key, Value) -> convertNode(Value) end, Revision)).
  
  mergeTrees({LsubTree, Ldata}, {RsubTree, Rdata}) ->
          NewData = lists:umerge(Ldata, Rdata),
  