public IEnumerable <POCO.User> FindByKeys(params int[] keys)
        {
            var specification = new Specification.User.ByKey(keys);

            var result = Find(specification);

            return(result);
        }
        public POCO.User FirstOrDefault(int key)
        {
            var specification = new Specification.User.ByKey(key);

            var result = Context.AsQueryable <POCO.User>().Where(specification.Predicate).FirstOrDefault();

            return(result);
        }