def options(self, *authorities):
        """
        Create a context factory using this L{PrivateCertificate}'s certificate
        and private key.

        @param authorities: A list of L{Certificate} object

        @return: A context factory.
        @rtype: L{CertificateOptions <twisted.internet.ssl.CertificateOptions>}
        """
        options = dict(privateKey=self.privateKey.original,
                       certificate=self.original)
        if authorities:
            options.update(dict(trustRoot=OpenSSLCertificateAuthorities(
                [auth.original for auth in authorities]
            )))
        return OpenSSLCertificateOptions(**options)

        Create a context factory using this L{PrivateCertificate}'s certificate
        and private key.

        @param authorities: A list of L{Certificate} object

        @return: A context factory.
        @rtype: L{CertificateOptions <twisted.internet.ssl.CertificateOptions>}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/_sslverify.py