{"ast_node_type":"variable","tokens":[{"end":71,"kind":"keyword","start":0,"text":"let"}]}
        let crate_data = Arc::get_mut(&mut self.def_map.data).unwrap();
        self.define_proc_macro(def.name.clone(), proc_macro_id);
        if let ProcMacroKind::Derive { helpers } = def.kind {