public IActionResult GetById(int id)
        {
            var author = _authorRepository.FindByID(id);

            if (author == null)
            {
                return(Ok("Author doesn't exist!"));
            }
            return(Ok(author));
        }
        public IActionResult GetById(long id)
        {
            var item = authorRepository.FindByID(id);

            if (item == null)
            {
                return(NotFound("Author with id : " + id + " is not present. Enter valid author id."));
            }
            return(Ok(item));
        }