Stop the GNS3 VM

def _stop(self):
        """
        Stop the GNS3 VM
        """
        engine = self.current_engine()
        if "vm" in self._controller.computes:
            yield from self._controller.delete_compute("vm")
        if engine.running:
            log.info("Stop the GNS3 VM")
            yield from engine.stop()