message: implement size_hint() and ExactSizeIterator for VectorOf...
diff: @@ -107,6 +107,19 @@ impl<T, S> Iterator for VectorIterator<T>
  self.i += 1;
  out.ok()
  }
  +
  + fn size_hint(&self) -> (usize, Option<usize>) {
  + (self.vec.len(), None)
  + }
  +}
  +
  +impl<T, S> ExactSizeIterator for VectorIterator<T>
  + where
  + T: for<'i> Vector<'i, Storage=S>
  +{
  + fn len(&self) -> usize {
  + self.vec.len()
  + }
  }
  pub struct VectorRefIterator<'v, T> {
  @@ -131,6 +144,17 @@ impl<T, S> Iterator for VectorRefIterator<'_, T>
  self.i += 1;
  out.ok()
  }
  -}
  + fn size_hint(&self) -> (usize, Option<usize>) {
  + (self.vec.len(), None)
  + }
  +}
  +impl<T, S> ExactSizeIterator for VectorRefIterator<'_, T>
  + where
  + T: for<'i> Vector<'i, Storage=S>
  +{
  + fn len(&self) -> usize {
  + self.vec.len()
  + }
  +}
  