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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_day_of_month(datestring):
 """Transforms an ordinal number into plain number with padding zero. E.g. 3rd -> 03, or 12th -> 12 Keyword arguments: datestring -- a string Returns: String, or None if the transformation fails """

    get_day = re.compile(r"\d{1,2}(st|nd|rd|th)?", re.IGNORECASE)
    day = get_day.search(datestring)
    the_day = None

    if day:
        if bool(re.search(r"[st|nd|rd|th]", day.group().lower())):
            the_day = day.group()[:-2]
        else:
            the_day = day.group()
        if int(the_day) < 10:
            the_day = add_zero(the_day)

    return str(the_day)