def rg(self):
        """
        Brazilian RG, return plain numbers.
        Check:  https://www.ngmatematica.com/2014/02/como-determinar-o-digito-verificador-do.html
        """

        digits = self.generator.random.sample(range(0, 9), 8)
        checksum = sum(i * digits[i - 2] for i in range(2, 10))
        last_digit = 11 - (checksum % 11)

        if last_digit == 10:
            digits.append('X')
        elif last_digit == 11:
            digits.append(0)
        else:
            digits.append(last_digit)

        return ''.join(map(str, digits))