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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 imei(self) -> str: """Generate a random IMEI. :return: IMEI. """

        num = self.random.choice(IMEI_TACS)
        num = num + str(self.random.randint(100000, 999999))
        return num + luhn_checksum(num)