internal override TypeDescription Clone(Dictionary <TypeDescription, TypeDescription> backRefLookup) { if (backRefLookup.ContainsKey(this)) { return(backRefLookup[this]); } var ret = new DictionaryTypeDescription(); backRefLookup[this] = ret; ret.KeyType = KeyType.Clone(backRefLookup); ret.ValueType = ValueType.Clone(backRefLookup); return(ret); }