Fixup: Notation of parameters for avl_equal()
Fixup: avl_equal(): If the ptrs are equal, the set is equal. If either of the ptrs is NULL and the other isnt, the set is not equal
Fixup: avl_equal(): complex condition with simple xor replaced
Fixup: ll_equal(): if ptrs are equal, true, if ptrs are not equal because one is NULL, false
Fixup: ll_equal(): Complex condition with simple xor replaced