def setUp(self):
        """
        Set up client and server SSL contexts for use later.
        """
        self.sKey, self.sCert = makeCertificate(
            O="Server Test Certificate",
            CN="server")
        self.cKey, self.cCert = makeCertificate(
            O="Client Test Certificate",
            CN="client")
        self.serverSSLContext = CertificateOptions(
            privateKey=self.sKey,
            certificate=self.sCert,
            requireCertificate=False)
        self.clientSSLContext = CertificateOptions(
            requireCertificate=False)

        Set up client and server SSL contexts for use later.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py