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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 generate_totp(secret, period=30, timestamp=None):
 """Generate a TOTP code. A TOTP code is an extension of HOTP algorithm. :param secret: A secret token for the authentication. :param period: A period that a TOTP code is valid in seconds :param timestamp: Current time stamp. """

    if timestamp is None:
        timestamp = time.time()
    counter = int(timestamp) // period
    return generate_hotp(secret, counter)