code: def close(self):
          
          # Stop the comm thread
          self._thread.stop()
  
          # Close the USB dongle
          try:
              if self.cfusb:
                  self.cfusb.set_crtp_to_usb(False)
                  self.cfusb.close()
          except Exception as e:
              # If we pull out the dongle we will not make this call
              logger.info('Could not close {}'.format(e))
              pass
          self.cfusb = None
docs: Close the link.