private IEnumerable<Weight> SuggestConvertions (Weight weight)
    => new List<Weight>
       {
           weight.kg(),
           weight.hg(),
           weight.dag(),
           weight.g(),
           weight.dg(),
           weight.cg(),
           weight.mg(),
           weight.lb(),
           weight.oz(),
       }.Where(w => w.OriginalUnit != weight.OriginalUnit);