'Creates a server block for a challenge.
:param achall: Annotated TLS-SNI-01 challenge
:type achall:
:class:`certbot.achallenges.KeyAuthorizationAnnotatedChallenge`
:param list addrs: addresses of challenged domain
:class:`list` of type :class:`~nginx.obj.Addr`
:returns: server block for the challenge host
:rtype: list'

def _make_server_block(self, achall, addrs):

    document_root = os.path.join(self.configurator.config.work_dir, 'tls_sni_01_page')
    block = [['listen', '    ', addr.to_string(include_default=False)] for addr in addrs]
    block.extend([['server_name', '    ', achall.response(achall.account_key).z_domain.decode('ascii')], ['access_log', '    ', os.path.join(self.configurator.config.work_dir, 'access.log')], ['error_log', '    ', os.path.join(self.configurator.config.work_dir, 'error.log')], ['ssl_certificate', '    ', self.get_cert_path(achall)], ['ssl_certificate_key', '    ', self.get_key_path(achall)], ['include', '    ', self.configurator.mod_ssl_conf], [['location', '    ', '/'], [['root', '    ', document_root]]]])
    return [['server'], block]
