checkEndOfDomain example

        if ($this->lexer->current->isA(EmailLexer::S_AT)) {
            return new InvalidEmail(new ConsecutiveAt(), $this->lexer->current->value);
        }

        $result = $this->doParseDomainPart();
        if ($result->isInvalid()) {
            return $result;
        }

        $end = $this->checkEndOfDomain();
        if ($end->isInvalid()) {
            return $end;
        }

        $this->lexer->stopRecording();
        $this->domainPart = $this->lexer->getAccumulatedValues();

        $length = strlen($this->domainPart);
        if ($length > self::DOMAIN_MAX_LENGTH) {
            return new InvalidEmail(new DomainTooLong(), $this->lexer->current->value);
        }