Function retry_with_backoff 

pub async fn retry_with_backoff<T, E, Fut, F>(
    operation: F,
    max_attempts: usize,
    init_backoff: Duration,
    max_backoff: Duration,
) -> Result<T, E>
where
    F: FnMut() -> Fut,
    Fut: Future<Output = Result<T, E>>,
    E: Debug,