public interface IRepository<T> : IProject<T> where T : class, new() {
  T Get(int id);
  T GetFirst(Expression<Func<T, bool>> condition);
  IEnumerable<T> GetAll();
  T SaveOrUpdate(T entity);
  IEnumerable<T> SaveOrUpdate(IEnumerable<T> entities);
  void Delete(T item);
  // other various operations on your repository of choice ...
}