public function negativeMatch(string $name, $subject, array $arguments): ?\PhpSpec\Wrapper\DelayedCall
    {
        if ($subject->equals($arguments[0])) {
            throw new FailureException('<label>' . get_class($subject) . "</label> <value>{$subject->toString()}</value> should not equal <value>{$arguments[0]->toString()}</value> but does.");
        }
    }