private XLoper convert(XLOper x) {
switch (x.type) {
case XLOperType.xltypeBool:
return new XLBool(x.bool);
case XLOperType.xltypeErr:
return new XLError(x.err);
case XLOperType.xltypeInt:
return new XLInt(x.w);
case XLOperType.xltypeMissing:
return XLMissing.MISSING;
case XLOperType.xltypeMulti: