public virtual bool IsNamedValue(string key, string ws)
 {
     if (ws != null)
     {
         var wsNames = _excelDataProvider.GetWorksheetNames(ws);
         if (wsNames != null && wsNames.ContainsKey(key))
         {
             return(true);
         }
     }
     return(_values != null && _values.ContainsKey(key));
 }