code: def read(self, sensors):
          
          payload = {'destDev': [], 'keys': list(set([s.key for s in sensors]))}
          if self.sma_sid is None:
              yield from self.new_session()
              if self.sma_sid is None:
                  return False
          body = yield from self._fetch_json(URL_VALUES, payload=payload)
  
          # On the first 401 error we close the session which will re-login
          if body.get('err') == 401:
              _LOGGER.warning("401 error detected, closing session to force "
                              "another login attempt")
              self.close_session()
              return False
  
          _LOGGER.debug(json.dumps(body))
          for sen in sensors:
              if sen.extract_value(body):
                  _LOGGER.debug("%s\t= %s %s",
                                sen.name, sen.value, sen.unit)
          return True
docs: Read a set of keys.