public int CompareTo(ContactAttributes other)
 {
     if (Object.ReferenceEquals(other, null))
     {
         return(1);
     }
     if (LastnameContact.CompareTo(other.LastnameContact) == 0)
     {
         return(FirstnameContact.CompareTo(other.FirstnameContact));
     }
     else
     {
         return(LastnameContact.CompareTo(other.LastnameContact));
     }
 }
 public override int GetHashCode()
 {
     return(FirstnameContact.GetHashCode());
 }