def remove_user_from_sheet(request, slug):
username = request.GET['username']
if username and username != request.user.username:
user = get_object_or_404(User, username=username)
sheet = get_object_or_404(Sheet, slug=slug)
MarkAPI.delete_marks_for_student(user)
remove_perm('sheets.view_sheet', user, sheet)
remove_perm('sheets.change_sheet', user, sheet)
return redirect('sheet_detail', slug=slug)
