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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 get_week_URL(date, day=0):
 """ Returns the week view URL for a given date. :param date: A date instance. :param day: Day number in a month. """

    if day < 1:
        day = 1
    date = datetime(year=date.year, month=date.month, day=day, tzinfo=utc)
    return reverse('calendar_week', kwargs={'year': date.isocalendar()[0],
                                            'week': date.isocalendar()[1]})