{"ast_node_type":"variable","tokens":[{"end":39,"kind":"keyword","start":0,"text":"let"}]}
        let disable_unstable_features =
        // `true` if this is a feature-staged build, i.e., on the beta or stable channel.
            option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some_and(|s| s != "0");