{"ast_node_type":"function","tokens":[{"end":83,"kind":"keyword","start":0,"text":"Some(self_param)"}]}
        Some(self_param) if args.is_empty() => format!("fn f({self_param}) {{ }}"),
    let list = match self_param {
        Some(self_param) => format!("fn f({self_param}, {args}) {{ }}"),