{"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"let"}]}
    let adt = ast::Adt::cast(item.syntax().clone())
        macro_items.items().next().ok_or_else(|| ExpandError::other(call_site, "no item found"))?;
        .ok_or_else(|| ExpandError::other(call_site, "expected struct, enum or union"))?;