// Place local declarations here.
int[0,9] valid_pin[PIN_LENGTH] = {1,2,3,4};

bool checkIfPINDigitIsValid (){
    return is_pin_valid && pin_iterator < PIN_LENGTH && pin[pin_iterator] == valid_pin[pin_iterator];
}

bool checkIfPINDigitIsNotValid (){
    return is_pin_valid && pin_iterator < PIN_LENGTH && pin[pin_iterator] != valid_pin[pin_iterator];
}