def METHOD_NAME(self, request, object_id, version_id, extra_context=None):
    """Actually compare two versions."""
    opts = self.model._meta
    object_id = unquote(object_id)
    # get_for_object's ordering means this is always the latest revision.
    # The reversion we want to compare to
    current = Version.objects.get_for_object_reference(self.model, object_id)[0]
    revision = Version.objects.get_for_object_reference(self.model, object_id).filter(id=version_id)[0]
    the_diff = make_diff(current, revision)
    context = {
        "title": _("Comparing current %(model)s with revision created %(date)s") % {
            'model': current,
            'date': get_date(revision),
            },
        "opts": opts,
        "compare_list_url": reverse("%s:%s_%s_comparelist" % (self.admin_site.name, opts.app_label, opts.model_name),
                                    args=(quote(object_id),)),
        "diff_list": the_diff,
    }
    extra_context = extra_context or {}
    context.update(extra_context)
    return render(request, self.compare_template or self._get_template_list("compare.html"),
                  context)