fn validate_unique_client_ids_inner(
input: Vec<GutenbergBlock>,
seen_ids: Rc<RefCell<HashSet<Uuid>>>,
) -> UtilResult<Vec<GutenbergBlock>>
fn validate_unique_client_ids_inner(
input: Vec<GutenbergBlock>,
seen_ids: Rc<RefCell<HashSet<Uuid>>>,
) -> UtilResult<Vec<GutenbergBlock>>