public virtual Task<List<IKupac>> GetRangeAsync(KupacFilter filter = null)
 {
     try
     {
         return Repository.GetRangeAsync(filter);
     }
     catch (Exception e)
     {
         throw e;
     }
 }
 /// <summary>
 /// Gets all customers (kupacs) async.
 /// </summary>
 /// <param name="filter"></param>
 /// <returns>The customers.</returns>
 public virtual Task<IEnumerable<IKupac>> GetAsync(KupacFilter filter = null)
 {
     try
     {
         return Repository.GetAsync(filter);
     }
     catch (Exception e)
     {
         throw e;
     }
 }