{"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
            let false_val = self.insert_bool(false);
            let ty = Ty::new_tup(self.tcx, &[self.ty(result), self.tcx.types.bool]);
            Some(self.insert_tuple(ty, vec![result, false_val]))