public List<E> SelectAll(string entitySetName, ISpecification<E> where)
        {
            return DoQuery(entitySetName, where).ToList();
        }

 public interface ISpecification<E>
    {
        /// <summary>
        /// Select/Where Expression
        /// </summary>
        Expression<Func<E, bool>> EvalPredicate { get; }
        /// <summary>
        /// Function to evaluate where Expression
        /// </summary>
        Func<E, bool> EvalFunc { get; }
    }

       System.Linq.Expressions.Expression<Func<Bank, bool>> expr = i => i.BIK == "" || i.City == ""; ;
             Specification<Bank> spec   = new Specification<Bank>(expr);
             return BankManagementRepository.SelectAll(spec);