def pipe(self):
        """
        Create a non-blocking pipe which will be closed after the currently
        running test.
        """
        read, write = os.pipe()
        self.addCleanup(os.close, read)
        self.addCleanup(os.close, write)
        setNonBlocking(read)
        setNonBlocking(write)
        return read, write

        Create a non-blocking pipe which will be closed after the currently
        running test.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_sigchld.py