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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 conferences(self):
 """ Access the conferences :returns: twilio.rest.api.v2010.account.conference.ConferenceList :rtype: twilio.rest.api.v2010.account.conference.ConferenceList """

        if self._conferences is None:
            self._conferences = ConferenceList(self._version, account_sid=self._solution['sid'], )
        return self._conferences