def index(request):
    """
    Listing page for event `Occurrence`s.

    :param request: Django request object.
    :param is_preview: Should the listing page be generated as a preview? This
                       will allow preview specific actions to be done in the
                       template such as turning off tracking options or adding
                       links to the admin.
    :return: TemplateResponse
    """
    warnings.warn(
        "icekit_events.views.index is deprecated and will disappear in a "
        "future version. If you need this code, copy it into your project."
        , DeprecationWarning
    )

    occurrences = models.Occurrence.objects.visible()
    context = {
        'occurrences': occurrences,
    }
    return TemplateResponse(request, 'icekit_events/index.html', context)