message: Use SmallMap::insert_hashed_unique_unchecked
  Summary: Generate slightly more efficient code.
diff: @@ -421,7 +421,7 @@ impl<'v, V: ValueLike<'v>> ParametersSpec<V> {
  match &mut self.kwargs {
  None => {
  let mut mp = SmallMap::with_capacity_largest_vec();
  - mp.insert_hashed(key, val);
  + mp.insert_hashed_unique_unchecked(key, val);
  self.kwargs = Some(mp);
  false
  }
  