message: Update iterative_hash example.
diff: use blake2::{Blake2b, Digest};
  +use std::time::{Duration, SystemTime};
  fn main() {
  let mut data: Vec<u8> = b"test".to_vec();
  + let now = SystemTime::now();
  +
  + let mut last_millis: u128 = 0;
  + let mut round_count: usize = 0;
  for i in 0.. {
  let mut hasher = Blake2b::new();
  @@ -9,8 +14,11 @@ fn main() {
  let out = hasher.result();
  data = out.to_vec();
  - if i % 1000000 == 0 {
  - println!("Round {}: {:?}", i, data);
  + if i % 100000 == 0 {
  + let millis = now.elapsed().unwrap().as_millis();
  + println!("{} rounds in last second", (i - round_count) as f64 / (millis - last_millis) as f64);
  + last_millis = millis;
  + round_count = i;
  }
  }
  }
  