<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def __get_last_update_time():
    '''Returns last FTP site update time'''
    now = datetime.datetime.utcnow()

    # Get the first Tuesday of the month
    first_tuesday = __get_first_tuesday(now)

    if first_tuesday < now:
        return first_tuesday
    else:
        first_of_month = datetime.datetime(now.year, now.month, 1)
        last_month = first_of_month + datetime.timedelta(days=-1)
        return __get_first_tuesday(last_month)