/// <summary>
 /// Returns true if the selected users are friends, false otherwise
 /// </summary>
 /// <param name="firstUserId"></param>
 /// <param name="secondUserId"></param>
 /// <returns></returns>
 public bool AreFriends(long firstUserId, long secondUserId)
 {
     return(firstUserId < secondUserId?_fr.AreFriends(firstUserId, secondUserId) : _fr.AreFriends(secondUserId, firstUserId));
 }