{"ast_node_type":"variable","tokens":[{"end":95,"kind":"keyword","start":0,"text":"let"}]}
            let allowed_by_implication = implied_by.is_some_and(|feature| is_allowed(feature));
                |feature| self.tcx.features().enabled(feature) || span.allows_unstable(feature);
            if !is_allowed(feature) && !allowed_by_implication {