code: def join_event_view(request, id):
      
  
      event = get_object_or_404(Event, id=id)
  
      if request.method == "POST":
          if not event.show_attending:
              return redirect("events")
          if "attending" in request.POST:
              attending = request.POST.get("attending")
              attending = (attending == "true")
  
              if attending:
                  event.attending.add(request.user)
              else:
                  event.attending.remove(request.user)
  
              return redirect("events")
  
      context = {"event": event, "is_events_admin": request.user.has_admin_permission('events')}
      return render(request, "events/join_event.html", context)
docs: Join event page. If a POST request, actually add or remove the attendance of the current
      user. Otherwise, display a page with confirmation.
  
      id: event id