class Member {
 	String emailAddress;
 	
 	public boolean isValid() {
 	    return emailAddress.matches("^\\S+@\\S+\\.\\S+$");
 	}
 }
@Getter
public class Member {
    String emailAddress;
    boolean emailVerified;
}

public interface VerifyEmailService {
    boolean verify(String emailAddress);
}

public class VerifyEmailUseCase {
    private VerifyEmailService verifyEmailService;
    private SaveMemberPort saveMemberPort;
    
    public void verify(VerifyEmailCommand command) {
        if (verifyEmailService.verify(command.getEmailAddress())) {
            Member member = new Member(command.getEmailAddress(), true);
            saveMemberPort.save(member);
        } else {
            throw new FailToVerifyEmailException();
        }
    }
}

@Getter
public abstract class EmailAddress {
    String value;
}

public class VerifiedEmailAddress extends EmailAddress {
    VerifiedEmailAddress(String value) {
        super(value);
    }
}

public class UnverifiedEmailAddress extends EmailAddress {
    public UnverifiedEmailAddress(String value) {
        super(value);
    }
}

public class Member {
    EmailAddress emailAddress;
}

public interface VerifyEmailService {
    VerifiedEmailAddress verify(UnverifiedEmailAddress emailAddress);
}

public interface SendNotificationService {
    void send(VerifiedEmailAddress emailAddress);
}