Function retry::retry_exponentially

pub fn retry_exponentially<F, G, R>(
    tries: u64, 
    wait: f64, 
    value_fn: F, 
    condition_fn: G
) -> Result<R, RetryError> where
    F: FnMut() -> R,
    G: FnMut(&R) -> bool, 

Invokes a function a certain number of times or until a condition is satisfied with an exponential backoff after each unsuccessful try.