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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 parseDtstart(contentline, allowSignatureMismatch=False):
 """ Convert a contentline's value into a date or date-time. A variety of clients don't serialize dates with the appropriate VALUE parameter, so rather than failing on these (technically invalid) lines, if allowSignatureMismatch is True, try to parse both varieties. """

    tzinfo = getTzid(getattr(contentline, 'tzid_param', None))
    valueParam = getattr(contentline, 'value_param', 'DATE-TIME').upper()
    if valueParam == "DATE":
        return stringToDate(contentline.value)
    elif valueParam == "DATE-TIME":
        try:
            return stringToDateTime(contentline.value, tzinfo)
        except:
            if allowSignatureMismatch:
                return stringToDate(contentline.value)
            else:
                raise