code: def set_preferences(self, **kwargs):
          
          json_data = "json={}".format(json.dumps(kwargs))
          headers = {'content-type': 'application/x-www-form-urlencoded'}
          return self._post('command/setPreferences', data=json_data,
                            headers=headers)
docs: Set preferences of qBittorrent.
          Read all possible preferences @ http://git.io/vEgDQ
  
          :param kwargs: set preferences in kwargs form.