code: def _start_scan(self, active):
          
  
          success, retval = self._set_scan_parameters(active=active)
          if not success:
              return success, retval
  
          try:
              response = self._send_command(6, 2, [2])
              if response.payload[0] != 0:
                  self._logger.error('Error starting scan for devices, error=%d', response.payload[0])
                  return False, {'reason': "Could not initiate scan for ble devices, error_code=%d, response=%s" % (response.payload[0], response)}
          except InternalTimeoutError:
              return False, {'reason': "Timeout waiting for response"}
  
          return True, None
docs: Begin scanning forever