protected void lb_studdelete_Click(object sender, EventArgs e)
        {
            LinkButton lb = (LinkButton)sender;
            var        id = int.Parse(lb.CommandArgument);

            var courseToRemove = cc.CourseByID(id);
            var gc             = new GradesControl();

            var gradesToRemove = gc.GetAllGrades().ToList().Where(x => x.CourseID == courseToRemove.Id);

            foreach (var grade in gradesToRemove)
            {
                gc.RemoveGrade(grade);
            }

            var ac = new AttendanceControl();
            var attendanceToRemove = ac.GetAllAttendance().ToList().Where(a => a.CourseID == courseToRemove.Id);

            foreach (var attendance in attendanceToRemove)
            {
                ac.RemoveAttendance(attendance);
            }

            cc.RemoveCourse(courseToRemove);

            Response.Redirect($"Course");
        }
        protected void LinkButton1_Click(object sender, EventArgs e)
        {
            LinkButton lb = (LinkButton)sender;
            var        id = lb.CommandArgument;

            var gc = new GradesControl();

            int studID               = int.Parse(Request.QueryString["StudentID"]);
            int courseID             = int.Parse(id);
            var studentGradeToRemove = gc.GradeByStudentAndCourseID(studID, courseID);

            gc.RemoveGrade(studentGradeToRemove);

            Response.Redirect($"Course?StudentID={studID}");
        }