public bool Equals(ORDictionary <TKey, ORSet <TValue> > .IDeltaOperation other)
            {
                if (other is ORDictionary <TKey, ORSet <TValue> > .DeltaGroup group)
                {
                    if (Underlying is ORDictionary <TKey, ORSet <TValue> > .DeltaGroup ourGroup)
                    {
                        return(ourGroup.Operations.SequenceEqual(group.Operations));
                    }

                    if (group.Operations.Length == 1)
                    {
                        return(Underlying.Equals(group.Operations.First()));
                    }

                    return(false);
                }
                return(Underlying.Equals(other));
            }