{"ast_node_type":"variable","tokens":[{"end":13,"kind":"keyword","start":0,"text":"let"}]}
    let fty =
    let hir_id = tcx.local_def_id_to_hir_id(def_id);
        ItemCtxt::new(tcx, def_id).lowerer().lower_fn_ty(hir_id, safety, abi, decl, None, None);