async void ClickMe(System.Object sender, System.EventArgs e)
        {
            try
            {
                _fireAuth = _firebaseAuth.Value;
                await _fireAuth.VerifyPhoneNumberAsync(phoneEntry.Text);

                await Navigation.PushAsync(new OTPVerifyPage(_fireAuth));
            }
            catch (FirebaseException ex)
            {
                await DisplayAlert("Error", ex.Message, "Okay");
            }
            catch (Exception ex)
            {
                await DisplayAlert("Error", ex.Message, "Okay");
            }
        }
 public IObservable <Unit> VerifyPhoneNumber(string phoneNumber)
 {
     return(_firebaseAuth.VerifyPhoneNumberAsync(phoneNumber).ToObservable());
 }