message: use an iterator for trailing_zeros
diff: @@ -1633,14 +1633,12 @@ impl BigUint {
  // self is assumed to be normalized
  fn trailing_zeros(&self) -> usize {
  - let mut zeros = 0;
  - for &bigdigit in self.data.iter() {
  - zeros += bigdigit.trailing_zeros() as usize;
  - if bigdigit != 0 {
  - break
  - }
  - }
  - zeros
  + self.data
  + .iter()
  + .enumerate()
  + .find(|&(_, &digit)| digit != 0)
  + .map(|(i, digit)| i * big_digit::BITS + digit.trailing_zeros() as usize)
  + .unwrap_or(0)
  }
  /// Strips off trailing zero bigdigits - comparisons require the last element in the vector to
  