message: a sacrifice for clippy
diff: @@ -470,7 +470,7 @@ impl Handler for VnHandler {
  }
  fn rewrite_out(&mut self, dgrams: &mut Vec<Datagram>) {
  - if dgrams.len() == 0 {
  + if dgrams.is_empty() {
  return;
  }
  assert!(dgrams.len() == 1);
  @@ -660,9 +660,9 @@ fn main() {
  }
  }
  let mut letter_str = String::from("");
  - for l in vec!['V', 'H', 'D', 'C', 'R', 'Z', 'S', '3'] {
  - if all_letters.contains(&l) {
  - letter_str.push(l);
  + for l in &['V', 'H', 'D', 'C', 'R', 'Z', 'S', '3'] {
  + if all_letters.contains(l) {
  + letter_str.push(*l);
  }
  }
  println!("{}: {} -> {:?}", child.0.label, letter_str, res);
  