//Add data to the stream
  Function(String) get changeEmail => _emailController.sink.add;
  Function(String) get changePassword => _passwordController.sink.add;

//Retreive data from the stream
  Stream<String> get email => _emailController.stream
      .transform(validateEmail); //Return the transformed stream
  Stream<String> get password =>
      _passwordController.stream.transform(validatePassword);