/**
  * Validate verification for the given credentials.
  *
  * @param array $credentials
  * @return \Krucas\LaravelUserEmailVerification\Contracts\RequiresEmailVerification
  */
 protected function validateVerification(array $credentials)
 {
     if (is_null($user = $this->getUser($credentials))) {
         return Contracts\VerificationBroker::INVALID_USER;
     }
     if (!$this->tokens->exists($user, $credentials['token'])) {
         return Contracts\VerificationBroker::INVALID_TOKEN;
     }
     return $user;
 }