def test_release(self):
        """
        L{_ExhaustsFileDescriptors.release} releases all opened
        file descriptors.
        """
        self.exhauster.exhaust()
        self.exhauster.release()
        # Does not fail with EMFILE
        self.openAFile()

        L{_ExhaustsFileDescriptors.release} releases all opened
        file descriptors.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_tcp.py