Function retry 

pub async fn retry<F, U, E, Fut>(
    retry_params: &RetryParams,
    f: F,
) -> Result<U, E>
where
    F: Fn() -> Fut,
    Fut: Future<Output = Result<U, E>>,
    E: Retryable + Display + 'static,

Retry with exponential backoff and full jitter. Implementation and default values originate from the Java SDK. See also: https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/.