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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 iso8601time(time_tuple):
 """Format time_tuple as a ISO8601 time string. :param time_tuple: Either None, to use the current time, or a tuple tuple. """

    if time_tuple:
        return time.strftime("%Y-%m-%dT%H:%M:%SZ", time_tuple)
    else:
        return time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())