text: public override ValueEval Evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0){ValueEval arg = arg0;if (arg is RefEval){RefEval re = (RefEval)arg;arg = re.GetInnerValueEval(re.FirstSheetIndex);}else if (arg is AreaEval){arg = ((AreaEval)arg).GetRelativeValue(0, 0);}if (arg is StringEval){return arg;}if (arg is ErrorEval){return arg;}return StringEval.EMPTY_INSTANCE;}