Django groups and permissions

I would like to create 2 groups (Professors, Students). And I would like to restrict students from creating and deleting Courses.

views.py:

def is_professor(function=None):

    def _is_professor(u):
      if user.groups.filter(name='Professor').exists():
          return True
      else:
          raise HttpResponseForbidden
  return _is_professor(function)

class ListCourseView(ListView):

    model = Course
    template_name = 'course_list.html'
    fields = '__all__'

@is_professor
class CreateCourseView(CreateView):

    def get_queryset(self, request):
        if not request.user.is_superuser:
             return False

    model = Course
    template_name = 'course/edit_course.html'
    fields = '__all__'

    def get_success_url(self):
        return reverse('courses-list')

    def get_context_data(self, **kwargs):

         context = super(CreateCourseView, self).get_context_data(**kwargs)
        context['action'] = reverse('courses-new')

        return context

class UpdateCourseView(UpdateView):

    model = Course
    template_name = 'course/edit_course.html'
    fields = '__all__'

    def get_success_url(self):
        return reverse('courses-list')

def get_context_data(self, **kwargs):

    context = super(UpdateCourseView, self).get_context_data(**kwargs)
    context['action'] = reverse('courses-edit',
                                kwargs={'pk': self.get_object().id})

    return context

class DeleteCourseView(DeleteView):

    model = Course
    template_name = 'course/delete_course.html'

    def get_success_url(self):
        return reverse('courses-list')

models.py

 class Course(models.Model):
    name = models.CharField(
    max_length=255,
    )

    def __str__(self):
        return ' '.join([
        self.name
        ])



class UserProfile(models.Model):
    user = models.OneToOneField(User)

    picture = models.ImageField(upload_to='profile_images', blank=True)

    class Meta:
        permissions = ( ('add_course', 'Add course'), )

    def __unicode__(self):
        return self.user.username

This is what I tried. First of all I get an error

NameError: global name 'user' is not defined.

And secondly I still don't think this would work :)