code: def get_activity_stream(self, before=None):
          
          if before:
              url = "https://www.duolingo.com/stream/{}?before={}"
              url = url.format(self.user_data.id, before)
          else:
              url = "https://www.duolingo.com/activity/{}"
              url = url.format(self.user_data.id)
          request = self._make_req(url)
          try:
              return request.json()
          except:
              raise Exception('Could not get activity stream')
docs: Get user's activity stream from
          ``https://www.duolingo.com/stream/<user_id>?before=<date> if before
          date is given or else
          ``https://www.duolingo.com/activity/<user_id>``
  
          :param before: Datetime in format '2015-07-06 05:42:24'
          :type before: str
          :rtype: dict