anchor.diff:  any_is_none_or_unit(Ts) ->
     lists:any(fun erl_types:t_is_none_or_unit/1, Ts).
   
  -all_is_none(Ts) ->
  -  lists:all(fun erl_types:t_is_none/1, Ts).
  -
   check_guard([X], Test, Type) ->
     check_guard_single(X, Test, Type).
   
  
positive.code: 		     case t_tuple_subtypes(Tuple) of
  		       unknown -> Ret;
  		       List ->
  			 Keys = [type(erlang, element, 2, [Y, S])
  				 || S <- List],
  			 Infs = [t_inf(Key, X) || Key <- Keys],
  			 case all_is_none(Infs) of
  			   true -> t_atom('false');
  			   false -> Ret
  			 end
  
negative.code: 		     case t_tuple_subtypes(Tuple) of
  		       unknown -> t_boolean();
  		       List ->
  			 case key_comparisons_fail(X, Y, List) of
  			   true -> t_atom('false');
  			   false -> t_boolean()
  			 end
  