Write a predicate not_unify/2 that indicates that both its arguments cannot be unified.

?- not_unify(42,42).
false.

?- not_unify(hug(panda,_),hug(_,octopus)).
false.

?- not_unify(42,1337).
true.

?- not_unify(hug(panda,_),hug(prolog,_)).
true.

Do not use \+, \= or =.