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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 by_month(self, chamber, year=None, month=None):
 """ Return votes for a single month, defaulting to the current month. """

        check_chamber(chamber)

        now = datetime.datetime.now()
        year = year or now.year
        month = month or now.month

        path = "{chamber}/votes/{year}/{month}.json".format(
            chamber=chamber, year=year, month=month)
        return self.fetch(path, parse=lambda r: r['results'])