override fun signIn(email: String, password: String): LiveData<FirebaseUser> {
    val loggedInUser: MutableLiveData<FirebaseUser> = MutableLiveData()

    mAuth.signInWithEmailAndPassword(email, password)
            .addOnCompleteListener {
                if (it.isSuccessful) {
                    loggedInUser.postValue(mAuth.currentUser)
                }
            }

    return loggedInUser
}

fun login() = Transformations.map(UserRemoteRepository.signIn(email.get().toString(), password.get().toString())) {
    it
}

override fun onActivityCreated(savedInstanceState: Bundle?) {
    super.onActivityCreated(savedInstanceState)
    val viewModel = viewDataBinding.viewmodel

    viewModel?.login()?.observe(this.activity, Observer {
        Log.d(TAG, it?.email)
    })
}