body = b''' 'use strict'; onconnect = (event) => { const port = event.ports[0]; port.onmessage = (event) => { fetch(event.data, { mode: 'no-cors' }) .then( () => port.postMessage('success'), () => port.postMessage('failure') ); }; port.postMessage('ready'); };''' def main(request, response): headers = [(b'Content-Type', b'text/javascript')] for value in request.GET.get_list(b'value'): headers.append((b'Cross-Origin-Embedder-Policy', value)) return (200, headers, body)