public bool isSubset(CSet aSet)
 {
     if (this.Size() > aSet.Size())
     {
         return(false);
     }
     else
     {
         foreach (Object key in this.data.Keys)
         {
             if (!(aSet.data.Contains(key)))
             {
                 return(false);
             }
         }
         return(true);
     }
 }