public void Sub(KeyedVectorPartial <TIndex> vec)
 {
     foreach (var pair in vec)
     {
         Dict[pair.Key] -= pair.Value;
     }
 }
 public bool IsBigger(KeyedVectorPartial <TIndex> smaller)
 {
     foreach (var pair in smaller)
     {
         if (pair.Value > this[pair.Key])
         {
             return(false);
         }
     }
     return(true);
 }