public async Task <IActionResult> RemoveSubscription([FromBody] Coursemembership sub)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            context.Coursemembership.Remove(sub);
            await context.SaveChangesAsync();

            return(NoContent());
        }
        public async Task <IActionResult> AddSubscription([FromBody] Coursemembership sub)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            context.Coursemembership.Add(sub);
            await context.SaveChangesAsync();

            return(Created("Successfully subscribed", sub));
        }