{"ast_node_type":"function","tokens":[{"end":42,"kind":"keyword","start":0,"text":"fn"}]}
    fn visit_ty(&mut self, ty: Ty<'tcx>) {
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for CollectParams<'_, 'tcx> {
        if let ty::Param(_) = ty.kind() {