anchor.diff:  	    lists:reverse(M, [])
       end.
   
  --spec ukeysort(pos_integer(), [T]) -> [T] when is_subtype(T, tuple()).
  +-spec ukeysort(pos_integer(), [T]) -> [T] when T :: tuple().
   
   ukeysort(I, L) when is_integer(I), I > 0 ->
       case L of
  
positive.code: 
  %% reverse(rumerge(reverse(A),reverse(B))) is equal to umerge(I,A,B).
  
  -spec rumerge([_], [_]) -> [_].
  
  rumerge(T1, []) ->
      T1;
  
negative.code: keystore2(_Key, _N, [], New) ->
      [New].
  
  -spec keysort(pos_integer(), [T]) -> [T] when T :: tuple().
  
  keysort(I, L) when is_integer(I), I > 0 ->
      case L of
  