P E N C I L
Login
Validator
  final _formKey = GlobalKey<FormState>();
  Form(key: _formKey, child: _body())
  
   _ok()  {
    if (!_formKey.currentState.validate()) return;
    }
TextFormField(
      validator: (value) {
        if (value.isEmpty) {
          return 'Required';
        }
        return null;
      },
    );
  

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