protected virtual void OnEvaluatingValueMember(ValueEventArgs <double?> e)
        {
            var handler = EvaluatingValueMember;

            handler?.Invoke(this, e);
        }
        protected virtual void OnEvaluatingCategory(ValueEventArgs <string> e)
        {
            var handler = EvaluatingCategory;

            handler?.Invoke(this, e);
        }