{"ast_node_type":"variable","tokens":[{"end":69,"kind":"keyword","start":0,"text":"let"}]}
        let origin = TypeVariableOrigin { span, param_def_id: None };
    pub fn next_ty_var_id_in_universe(&self, span: Span, universe: ty::UniverseIndex) -> TyVid {
        self.inner.borrow_mut().type_variables().new_var(universe, origin)