public IHttpActionResult GetLesson(int id)
        {
            String path = "Lessons\\" + id + ".txt";

            if (!File.Exists(path))
            {
                return(NotFound());
            }

            Lesson lesson = new Lesson();

            using (StreamReader sr = new StreamReader(path))
            {
                lesson.Fill(sr.ReadLine());

                while (!sr.EndOfStream)
                {
                    lesson.AddItem(sr.ReadLine());
                }
            }

            return(Ok(lesson));
        }