anchor.diff:      [{"abcdefghijklmnopqrstuvwxyz", 1}, {"aac", 2}, {"aabcde", 3}] =
           foldl(fun(K, V, A) -> [{K,V} | A] end, [], RootNode1),
       error = trie:find("aabcde", RootNode0),
  -    3 = trie:find("aabcde", RootNode1),
  +    {ok, 3} = trie:find("aabcde", RootNode1),
       RootNode2 = trie:erase("aac", RootNode0),
  -    1 = trie:find("abcdefghijklmnopqrstuvwxyz", RootNode2),
  +    {ok, 1} = trie:find("abcdefghijklmnopqrstuvwxyz", RootNode2),
       {97,98,{{{98,98,{{[],[2]}}},[1]},{"c",[3]}}} =
           RootNode3 = trie:new([{"a", [1]},{"ab", [2]},{"bc", [3]}]),
       {97,98,{{{98,98,{{[],[2]}}},[1,2]},{"c",[3]}}} =
  
positive.code:     {Node, Value} = erlang:element(H - I0 + 1, Data),
      if
          is_tuple(Node); Node == [] ->
              Value;
          true ->
              error
      end;
  
negative.code: %%% External interface functions
  %%%------------------------------------------------------------------------
  
  -type trie() :: [] | {integer(), integer(), tuple()}.
  -type trie_return() :: {integer(), integer(), tuple()}.
  
  %%-------------------------------------------------------------------------
  %% @doc
  %% ===Append a value as a list element in a trie instance.===
  %% @end
  %%-------------------------------------------------------------------------
  
  -spec append(Key :: string(),
               Value :: any(),
               Node :: trie()) -> trie_return().
  
  append([_ | _] = Key, Value, Node) ->
      ValueList = [Value],
      update(Key, fun(OldValue) -> OldValue ++ ValueList end, ValueList, Node).
  
  %%-------------------------------------------------------------------------
  %% @doc
  %% ===Append a list of values as a list element in a trie instance.===
  %% @end
  %%-------------------------------------------------------------------------
  
  -spec append_list(Key :: string(),
                    ValueList :: list(),
                    Node :: trie()) -> trie_return().
  
  append_list([_ | _] = Key, ValueList, Node) ->
      update(Key, fun(OldValue) -> OldValue ++ ValueList end, ValueList, Node).
  