code: def peripheral_didReadRSSI_error_(self, peripheral, rssi, error):
          
          logger.debug('peripheral_didReadRSSI_error called')
          # Note this appears to be completely undocumented at the time of this
          # writing.  Can see more details at:
          #  http://stackoverflow.com/questions/25952218/ios-8-corebluetooth-deprecated-rssi-methods
          # Stop if there was some kind of error.
          if error is not None:
              return
          # Notify the device about the updated RSSI value.
          device = device_list().get(peripheral)
          if device is not None:
              device._rssi_changed(rssi)
docs: Called when a new RSSI value for the peripheral is available.