internal abstract void DeclineBuddy(InstantMessageBuddy buddy);
 internal virtual void UnblockBuddy(InstantMessageBuddy buddy)
 {
     throw new NotImplementedException();
 }
 internal abstract void AcceptBuddy(InstantMessageBuddy buddy, InstantMessageGroup group);
 internal abstract void CopyBuddy(InstantMessageGroup group, InstantMessageBuddy buddy);
 internal abstract void MoveBuddy(InstantMessageGroup oldGroup, InstantMessageGroup newGroup, InstantMessageBuddy buddy);
 internal abstract void RemoveFromGroup(InstantMessageGroup group, InstantMessageBuddy buddy);
 internal abstract void RemoveBuddy(InstantMessageBuddy buddy);