create an implementation of business logic on RegistrationPresenter class.

RegistrationPresenter.swift

protocol RegistrationDelegate{
    func showProgress()
    func hideProgress()
    func registrationDidSucceed()
    func registrationDidFailed(message: String)
}

class RegistrationPresenter{
    var delegate: RegistrationDelegate
    
    init(delegate: RegistrationDelegate) {
        self.delegate = delegate
    }
    
    func register(email: String, password: String, fullName: String, phoneNumber:String){
        if email.isEmpty{
            print("omayib")
            self.delegate.registrationDidFailed(message: "email can't be blank")
        }
    }
    
}