title: how can i confirm password using formz in flutter
body: <p>When I want to confirm my password, but i can not compare the first and last passwords.</p>
  <p>Here my password class. It works fine, but confirmPassword section not.</p>
  <pre><code>class Password extends FormzInput&lt;String, PasswordValidationError&gt; {
    const Password.pure() : super.pure('');
    const Password.dirty([String value = '']) : super.dirty(value);
  
    static final _passwordRegExp = RegExp(r'^[A-Za-z\d@$!%*?&amp;]{8,}$');
  
    @override
    PasswordValidationError? validator(String value) {
      if (value.isEmpty) {
        return PasswordValidationError.empty;
      }
      return _passwordRegExp.hasMatch(value)
          ? null
          : PasswordValidationError.invalid;
    }
  }
  </code></pre>
  <p>You can ask what is the value in validator. Let me show you.</p>
  <pre><code>  void passwordChanged(String value) {
      final password = Password.dirty(value);
      emit(state.copyWith(
        password: password,
        status: Formz.validate(
            [state.name, state.email, password, state.confirmPassword]),
      ));
    }
  </code></pre>
  <p>This is my normal password field. Now let's look confirm section.</p>
  <pre><code>class ConfirmPassword
      extends FormzInput&lt;String, ConfirmedPasswordValidationError&gt; {
    const ConfirmPassword.pure() : super.pure('');
    const ConfirmPassword.dirty([String value = '']) : super.dirty(value);
  
    static final _confirmPasswordRegExp = RegExp(r'^[A-Za-z\d@$!%*?&amp;]{8,}$');
    
    @override
    ConfirmedPasswordValidationError? validator(String value) {
      if (value.isEmpty) {
        return ConfirmedPasswordValidationError.empty;
      } else if (!_confirmPasswordRegExp.hasMatch(value)) {
        return ConfirmedPasswordValidationError.invalid;
      }
      return (password**I mentioned here** == value)
          ? null
          : ConfirmedPasswordValidationError.mismatch;
    }
  }
  </code></pre>
  <p>and value in validator:</p>
  <pre><code>  void confirmPasswordChanged(String value) {
      final confirmPassword =
          ConfirmPassword.dirty(value);
      emit(state.copyWith(
        confirmPassword:
            state.password.valid ? confirmPassword : const ConfirmPassword.pure(),
        status: Formz.validate(
            [state.name, state.email, state.password, confirmPassword]),
      ));
    }
  </code></pre>
  <p>How can i reach the first (normal) value field in confirmPassword section? Or Is there any way to the use with formz?</p>