OtpTextField(
            numberOfFields: 5,
            borderColor: Color(0xFF512DA8),
            showFieldAsBox: true, //set to true to show as box or false to show as dash
            onCodeChanged: (String code) {
                //handle validation or checks here           
            },
            onSubmit: (String verificationCode){
              showDialog(
                  context: context,
                  builder: (context){
                    return AlertDialog(
                      title: Text("Verification Code"),
                      content: Text('Code entered is $verificationCode'),
                    );
                  }
              );
            }, // end onSubmit
          ),