/// <summary>
/// Check for any data of specified type.
/// </summary>
/// <typeparam name="TValue">data type</typeparam>
/// <param name="repository">queryable repository</param>
/// <returns>items has been found</returns>
public static bool Exists <TValue>(this IQueryableRepository <TValue> repository)
where TValue : IDataSource
{
Contract.Requires(repository != null);
return(repository.Exists <TValue>(null));
}