{"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"expected_ty:"}]}
        expected_ty: Ty<'tcx>,
        found_ty: Ty<'tcx>,
    ) -> Option<(Ty<'tcx>, Ty<'tcx>, Option<(Ty<'tcx>, Ty<'tcx>)>)> {