{"ast_node_type":"variable","tokens":[{"end":47,"kind":"keyword","start":0,"text":"let"}]}
        let def_id = def_id.into_query_param();
    pub fn opt_item_name(self, def_id: impl IntoQueryParam<DefId>) -> Option<Symbol> {
        if let Some(cnum) = def_id.as_crate_root() {