public static Proposition assertMemberOfProposition(Stella_Object self, Stella_Object collection) {
    if (collection == null) {
      return (null);
    }
    if (Surrogate.subtypeOfP(Stella_Object.safePrimaryType(collection), Logic.SGT_LOGIC_NAMED_DESCRIPTION)) {
      { NamedDescription collection000 = ((NamedDescription)(collection));

        if (collection000.surrogateValueInverse == Logic.SGT_STELLA_THING) {
          return (null);
        }
        return (Logic.assertIsaProposition(self, collection000.surrogateValueInverse));
      }
    }
    else {
      return (Logic.assertTuple(Logic.SGT_PL_KERNEL_KB_MEMBER_OF, Cons.consList(Cons.cons(self, Cons.cons(collection, Stella.NIL)))));
    }
  }