{"ast_node_type":"variable","tokens":[{"end":60,"kind":"keyword","start":0,"text":"let"}]}
    let main_fn_predicates = tcx.predicates_of(main_def_id);
    let main_fn_generics = tcx.generics_of(main_def_id);
    if main_fn_generics.count() != 0 || !main_fnsig.bound_vars().is_empty() {