anchor.diff:                                              lists:sublist(KeyValuesXC, 1, KeyNoXC)
                                           ]),
                                           lists:append([
  -                                            case SubtreeNoXCLeft == 0 of
  -                                                true ->
  +                                            case SubtreeNoXCLeft of
  +                                                0 ->
                                                       [];
                                                   _ ->
                                                       [lists:nth(SubtreeNoXCLeft, SubtreesXCLeft)]
  
positive.code:                                 KeyNoXCRight,
                                  SubtreeNoXCRight,
                                  KeyValuesXCRight,
                                  case SubtreeNoXC == 0 of
                                      true ->
                                          [];
                                      _ ->
                                          InsertFunction(
  
negative.code:                                     lists:append([
                                          lists:sublist(Subtrees, 1, KeyPos - 1),
                                          [{
                                              KeyNoXC + KeyNoXCRight, case SubtreeNoXCRight of
                                                                          0 ->
                                                                              0;
                                                                          _ ->
                                                                              SubtreeNoXC + SubtreeNoXCRight - 1
                                                                      end, lists:append([KeyValuesXC,
                                                  KeyValuesXCRight
                                              ]), case SubtreeNoXCRight of
                                                      0 ->
                                                          [];
                                                      _ ->
                                                          InsertFunction(
  