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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_series_vintage_dates(self, series_id):
 """ Get a list of vintage dates for a series. Vintage dates are the dates in history when a series' data values were revised or new data values were released. Parameters series_id : str Fred series id such as 'CPIAUCSL' Returns ------- dates : list list of vintage dates """

        url = "%s/series/vintagedates?series_id=%s" % (self.root_url, series_id)
        root = self.__fetch_data(url)
        if root is None:
            raise ValueError('No vintage date exists for series id: ' + series_id)
        dates = []
        for child in root.getchildren():
            dates.append(self._parse(child.text))
        return dates