docs: def session_callback(self, signal):
          """Signalling from stream session.
  
          Data - new data available for processing.
          Playing - Connection is healthy.
          Retry - if there is no connection to device.
          """
          if signal == SIGNAL_DATA:
              self.event.new_event(self.data)
  
          elif signal == SIGNAL_FAILED:
              self.retry()
  
          if signal in [SIGNAL_PLAYING, SIGNAL_FAILED] and \
                  self.connection_status_callback:
              self.connection_status_callback(signal)