'Return list of threads for the app.'

def list(self, request, app_slug):

    form = forms.AppSlugForm({'app': app_slug})
    if (not form.is_valid()):
        return Response('App    does    not    exist    or    no    app    slug    given', status=status.HTTP_404_NOT_FOUND)
    elif (not user_has_perm_app(request.user, form.cleaned_data['app'])):
        return Response('You    do    not    have    permissions    for    this    app', status=status.HTTP_403_FORBIDDEN)
    if (request.GET.get('serializer') == 'simple'):
        self.serializer_class = ThreadSimpleSerializer
    self.queryset = CommunicationThread.objects.filter(_addon=form.cleaned_data['app']).order_by('_version__version')
    return SilentListModelMixin.list(self, request)
