pub fn is_legitimate(pool: &[Vec<u8>]) -> Option<bool> {
    for row in pool {
        if *row.first()? == 1 || *row.last()? == 1 {
            return Some(false);
        }
    }
    for first_row in pool.first()? {
        if *first_row == 1 {
            return Some(false);
        }
    }
    for last_row in pool.last()? {
        if *last_row == 1 {
            return Some(false);
        }
    }

    Some(true)
}