def METHOD_NAME(client_acme, challb, orderr):
    """Set up standalone webserver and perform HTTP-01 challenge."""
    response, validation = challb.response_and_validation(client_acme.net.key)
    resource = standalone.HTTP01RequestHandler.HTTP01Resource(
        chall=challb.chall, response=response, validation=validation)
    with challenge_server({resource}):
        # Let the CA server know that we are ready for the challenge.
        client_acme.answer_challenge(challb, response)
        # Wait for challenge status and then issue a certificate.
        # It is possible to set a deadline time.
        finalized_orderr = client_acme.poll_and_finalize(orderr)
    return finalized_orderr.fullchain_pem