{"ast_node_type":"variable","tokens":[{"end":72,"kind":"keyword","start":0,"text":"let"}]}
    let kind_origin = typeck_results.closure_kind_origins().get(hir_id);
    let hir_id = tcx.local_def_id_to_hir_id(def);
    ClosureTypeInfo { user_provided_sig, captures, kind_origin }