def test_selectReturnsOnlyFromAvailable(self):
        """
        Select only returns a cross section of what is available and what is
        desirable.
        """
        ac = sslverify.OpenSSLAcceptableCiphers([
            sslverify.OpenSSLCipher('A'),
            sslverify.OpenSSLCipher('B'),
        ])
        self.assertEqual([sslverify.OpenSSLCipher('B')],
                         ac.selectCiphers([sslverify.OpenSSLCipher('B'),
                                           sslverify.OpenSSLCipher('C')]))

        Select only returns a cross section of what is available and what is
        desirable.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py