Generates a siret number (14 digits).
        It is in fact the result of the concatenation of a siren number (9 digits),
        a sequential number (4 digits) and a control number (1 digit) concatenation.
        If $max_sequential_digits is invalid, it is set to 2.
        :param max_sequential_digits The maximum number of digits for the sequential number (> 0 && <= 4).

def siret(self, max_sequential_digits=2):
        """
        Generates a siret number (14 digits).
        It is in fact the result of the concatenation of a siren number (9 digits),
        a sequential number (4 digits) and a control number (1 digit) concatenation.
        If $max_sequential_digits is invalid, it is set to 2.
        :param max_sequential_digits The maximum number of digits for the sequential number (> 0 && <= 4).
        """
        if max_sequential_digits > 4 or max_sequential_digits <= 0:
            max_sequential_digits = 2

        sequential_number = str(self.random_number(
            max_sequential_digits)).zfill(4)
        return self.numerify(self.siren() + ' ' + sequential_number + '#')