{"ast_node_type":"variable","tokens":[{"end":35,"kind":"keyword","start":0,"text":"let"}]}
    let ret_type = func.ret_type();
    let generic_param_list = parent_for_type.as_ref().and_then(|it| it.generic_param_list());
    let for_kw = parent_for_type.as_ref().and_then(|it| it.for_token());