private function equals(array $set1, array $set2): bool
    {
        return array_diff($set1, $set2) == array_diff($set2, $set1);
    }
private function equals(array $set1, array $set2): bool
    {
        return array_diff($set1, $set2) == array_diff($set2, $set1);
    }
private function equals ( array $ set1 , array $ set2 ) : bool { return array_diff ( $ set1 , $ set2 ) == array_diff ( $ set2 , $ set1 ) ; }
Returns true if string representation of items does not differ.

@param mixed[] $set1
@param mixed[] $set2
Returns true if string representation of items does not differ .