declare
%rest:path("/check/{$user}")
function page:check($user){
if($user = ('jack', 'lisa'))
then 'User exists'
%rest:error("err:user")
%rest:error-param("description", "{$user}")
function page:user-error($user){
'User "' || $user || '" is unknown'
};
declare
%rest:path("/teapot")
function page:teapot(){
fn:error(xs:QName('error'), "I'm a teapot", 418)
};