public bool RemoveFirst(out KeyValuePair <K, Vdest> value) { KeyValuePair <K, Vsrc> srcVal; var res = _innerMap.RemoveFirst(out srcVal); if (res) { value = new KeyValuePair <K, Vdest>(srcVal.Key, _srcToDest(srcVal.Value)); } else { value = default(KeyValuePair <K, Vdest>); } return(res); }