{"ast_node_type":"other","tokens":[{"end":78,"kind":"keyword","start":0,"text":"ty::FnDef(..)"}]}
                ty::FnDef(..) => cx.tcx.fn_sig(def_id).instantiate_identity(),
            let ty = match cx.tcx.type_of(def_id).instantiate_identity().kind() {
                ty::Closure(_, args) => args.as_closure().sig(),