def close(self):
        """
        Close the FD. If it's already been closed, do nothing.
        """
        if self._fd:
            close(self._fd)
            self._fd = None

        Close the FD. If it's already been closed, do nothing.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_sendmsg.py