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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def local_regon(self):
 """ Returns 14 character Polish National Business Registry Number, local entity number. https://pl.wikipedia.org/wiki/REGON """

        regon_digits = [int(digit) for digit in list(self.regon())]

        for _ in range(4):
            regon_digits.append(self.random_digit())

        regon_digits.append(local_regon_checksum(regon_digits))

        return ''.join(str(digit) for digit in regon_digits)