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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 valid_totp(self, code, period=30, timestamp=None):
 """Valid a TOTP code. :param code: A number that is less than 6 characters. :param period: A period that a TOTP code is valid in seconds :param timestamp: Validate TOTP at this given timestamp """

        if not valid_code(code):
            return False
        return compare_digest(
            bytes(self.totp(period, timestamp)),
            bytes(int(code))
        )