Function tweetr::util::span_r

pub fn span_r<F, R>(f: F) -> (ChronoDuration, R) where
    F: FnOnce() -> R, 

Runs a closure, returning the duration of time it took to run the closure and the closure's return value.

Equivalent to https://github.com/rust-lang-deprecated/time/pull/139

Examples

let (dur, i) = span_r(|| {
    thread::sleep(Duration::from_millis(10));
    420
});
assert_eq!(i, 420);
assert!(dur.num_milliseconds() >= 10);