/// <summary>
///
/// </summary>
/// <typeparam name="EntityType"></typeparam>
/// <typeparam name="TKey"></typeparam>
/// <param name="key"></param>
/// <returns></returns>
public virtual bool Exists <EntityType, TKey>(TKey key) where EntityType : class
{
return(services.ExistsByKey <EntityType, TKey>()(this, key));
}