bool append_body(JSContext *cx, HandleObject self, HandleObject source) {
  MOZ_ASSERT(!body_used(source));
  BodyHandle source_body = body_handle(source);
  BodyHandle dest_body = body_handle(self);
  return HANDLE_RESULT(cx, xqd_body_append(dest_body, source_body));
}
bool append_body(JSContext *cx, HandleObject self, HandleObject source) {
  MOZ_ASSERT(!body_used(source));
  BodyHandle source_body = body_handle(source);
  BodyHandle dest_body = body_handle(self);
  return HANDLE_RESULT(cx, xqd_body_append(dest_body, source_body));
}