def _prepare_conn(self, conn):
        """
        Prepare the ``connection`` for :meth:`urllib3.util.ssl_wrap_socket`
        and establish the tunnel if proxy is used.
        """

        if isinstance(conn, VerifiedHTTPSConnection):
            conn.set_cert(
                key_file=self.key_file,
                key_password=self.key_password,
                cert_file=self.cert_file,
                cert_reqs=self.cert_reqs,
                ca_certs=self.ca_certs,
                ca_cert_dir=self.ca_cert_dir,
                assert_hostname=self.assert_hostname,
                assert_fingerprint=self.assert_fingerprint,
            )
            conn.ssl_version = self.ssl_version
        return conn

        Prepare the ``connection`` for :meth:`urllib3.util.ssl_wrap_socket`
        and establish the tunnel if proxy is used.
        
product/gradle-plugin/src/main/python/pip/_vendor/urllib3/connectionpool.py