code: def out_endpoint(self):
          
          if getattr(self, '_out_endpoint', None) is None:
              config = self.device.get_active_configuration()
              interface_number = config[(0, 0)].bInterfaceNumber
              interface = usb.util.find_descriptor(config,
                      bInterfaceNumber=interface_number)
  
              self._out_endpoint = usb.util.find_descriptor(interface,
                      custom_match = \
                              lambda e: \
                              usb.util.endpoint_direction(e.bEndpointAddress) == \
                              usb.util.ENDPOINT_OUT)
  
              if not self._out_endpoint:
                  raise ControllerError(
                          "Couldn't find OUT endpoint on the USB device")
          return self._out_endpoint
docs: Open a reference to the USB device's only OUT endpoint. This method
          assumes that the USB device configuration has already been set.