def request(self, method, uri, headers=None, bodyProducer=None):
        """
        Issue a new request via the configured proxy.
        """
        uri = _ensureValidURI(uri.strip())

        # Cache *all* connections under the same key, since we are only
        # connecting to a single destination, the proxy:
        key = ("http-proxy", self._proxyEndpoint)

        # To support proxying HTTPS via CONNECT, we will use key
        # ("http-proxy-CONNECT", scheme, host, port), and an endpoint that
        # wraps _proxyEndpoint with an additional callback to do the CONNECT.
        return self._requestWithEndpoint(key, self._proxyEndpoint, method,
                                         URI.fromBytes(uri), headers,
                                         bodyProducer, uri)

        Issue a new request via the configured proxy.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/client.py