def stop_containers(self):
while len(self._containers):<EOL><INDENT>container = self._containers.pop()<EOL>try:<EOL><INDENT>container.kill(signal.SIGKILL)<EOL><DEDENT>except docker.errors.APIError:  <EOL><INDENT>pass<EOL><DEDENT><DEDENT>
Stops all containers used by this instance of the backend.