{"ast_node_type":"function","tokens":[{"end":80,"kind":"keyword","start":0,"text":"Some(trait_ref)"}]}
        Some(trait_ref) => format!("fn f(x: <{type_ref} as {trait_ref}>) {{}}"),
    let text = match trait_ref {
        None => format!("fn f(x: <{type_ref}>) {{}}"),