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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 advance_time_delta(timedelta):
 """Advance overridden time using a datetime.timedelta."""

    assert(utcnow.override_time is not None)
    try:
        for dt in utcnow.override_time:
            dt += timedelta
    except TypeError:
        utcnow.override_time += timedelta