public virtual bool Exists(TopLevelDomain id) => _repository.Contains(id);
/// <summary>
/// Checks whether an entity with the specified unique identifier exists.
/// </summary>
/// <param name="id">The unique identifier.</param>
/// <returns><c>true</c> if entity exists, <c>false</c> otherwise.</returns>
public virtual bool Exists(TId id)
{
return(_repository.Contains(id));
}