{"ast_node_type":"function","tokens":[{"end":94,"kind":"keyword","start":0,"text":"fn"}]}
    fn get_future_inner_return_ty(&self, hir_ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
    /// [`OpaqueDef`]: hir::TyKind::OpaqueDef
        let hir::TyKind::OpaqueDef(opaque_ty) = hir_ty.kind else {