anchor.diff:                                      lists:nth(1, SubtreesXCRight)
                                   }
                           end,
  -                    case KeyNo == 1 of
  -                        true ->
  +                    case KeyNo of
  +                        1 ->
                               {
                                   KeyNoXC + KeyNoXCRight,
                                   case SubtreeNoXCRight == 0 of
  
positive.code:                     end;
                  true ->
  % CLRS: case 3b right
                      case KeyNo == 1 of
                          true ->
                              delete_1(
                                  Key,
                                  {
  
negative.code:         none ->
              erlang:error({key_not_found, Key});
          _ ->
              {SubtreeNoMin, KeyNoMax, SizeKeyValues - 1, SortFunction, State, case KeyNo of
                                                                                   1 ->
                                                                                       nil;
                                                                                   _ ->
                                                                                       {
  