public override void ReadFrom(XElement xE)
 {
     base.ReadFrom(xE);
     Operand = null;
     foreach (var xItem in xE.Elements())
     {
         var localName = xItem.Name.LocalName;
         if (localName == "operand")
         {
             Operand = new AdGroupAdLabel();
             Operand.ReadFrom(xItem);
         }
     }
 }