How to use the orchestra.admin.utils.change_url function in orchestra

def get_absolute_url(self):
        return change_url(self)

def get_instance_url(operation):
    try:
        url = change_url(operation.instance)
    except NoReverseMatch:
        alt_repr = '%s-%s' % (operation.content_type, operation.object_id)
        return _("Deleted {0}").format(operation.instance_repr or alt_repr)
    return orchestra_settings.ORCHESTRA_SITE_URL + url

def display_forwards(self, mailbox):
        forwards = []
        for addr in mailbox.get_forwards():
            url = change_url(addr)
            forwards.append('<a href="%s">%s</a>' % (url, addr.email))
        return '<br>'.join(forwards)
    display_forwards.short_description = _("Forward from")

def display_webapps(self, website):
        webapps = []
        for content in website.content_set.all():
            webapp = content.webapp
            url = change_url(webapp)
            name = "%s on %s" % (webapp.get_type_display(), content.path or '/')
            webapps.append('<a href="%s">%s</a>' % (url, name))
        return '<br>'.join(webapps)
    display_webapps.allow_tags = True

if request.POST.get('post') == 'generic_confirmation':
        formset = SelectSourceFormSet(request.POST, request.FILES, queryset=queryset)
        if formset.is_valid():
            transactions = []
            for form in formset.forms:
                source = form.cleaned_data['source']
                transaction = form.instance.close(payment=source)
                if transaction:
                    transactions.append(transaction)
            for bill in queryset:
                modeladmin.log_change(request, bill, 'Closed')
            messages.success(request, _("Selected bills have been closed"))
            if transactions:
                num = len(transactions)
                if num == 1:
                    url = change_url(transactions[0])
                else:
                    url = reverse('admin:payments_transaction_changelist')
                    url += 'id__in=%s' % ','.join([str(t.id) for t in transactions])
                context = {
                    'url': url,
                    'num': num,
                }
                message = ungettext(
                    _('<a href="%(url)s">One related transaction</a> has been created') % context,
                    _('<a href="%(url)s">%(num)i related transactions</a> have been created') % context,
                    num)
                messages.success(request, mark_safe(message))
            return
    opts = modeladmin.model._meta
    context = {
        'title': _("Are you sure about closing the following bills?"),

def selected_related_choices(queryset):
    for order in queryset:
        verbose = '<a href="{order_url}">{description}</a> '
        verbose += '<a href="{account_url}" class="account">{account}</a>'
        if order.ignore:
            verbose += ' (ignored)'
        verbose = verbose.format(
            order_url=change_url(order), description=order.description,
            account_url=change_url(order.account), account=str(order.account)
        )
        yield (order.pk, mark_safe(verbose))

def display_databases(self, user):
        links = []
        for db in user.databases.all():
            link = '<a href="%s">%s</a>' % (change_url(db), db.name)
            links.append(link)
        return '<br>'.join(links)
    display_databases.short_description = _("Databases")

def confirmation(self, request):
        form = BillSelectConfirmationForm(initial=self.options)
        if int(request.POST.get('step')) >= 3:
            bills = self.queryset.bill(commit=True, **self.options)
            for order in self.queryset:
                self.modeladmin.log_change(request, order, _("Billed"))
            if not bills:
                msg = _("Selected orders do not have pending billing")
                self.modeladmin.message_user(request, msg, messages.WARNING)
            else:
                num = len(bills)
                if num == 1:
                    url = change_url(bills[0])
                else:
                    url = reverse('admin:bills_bill_changelist')
                    ids = ','.join([str(b.id) for b in bills])
                    url += '?id__in=%s' % ids
                msg = ungettext(
                    '<a href="{url}">One bill</a> has been created.',
                    '<a href="{url}">{num} bills</a> have been created.',
                    num).format(url=url, num=num)
                msg = mark_safe(msg)
                self.modeladmin.message_user(request, msg, messages.INFO)
            return
        bills = self.queryset.bill(commit=False, **self.options)
        bills_with_total = []
        for account, lines in bills:
            total = 0
            for line in lines:

def __init__(self, *args, **kwargs):
        super(SaaSBaseForm, self).__init__(*args, **kwargs)
        self.is_change = bool(self.instance and self.instance.pk)
        if self.is_change:
            site_domain = self.instance.get_site_domain()
            if self.instance.custom_url:
                try:
                    website = self.instance.service_instance.get_website()
                except ObjectDoesNotExist:
                    link = ('<br><span style="color:red"><b>Warning:</b> '
                            'Related website directive does not exist for %s URL !</span>' % 
                            self.instance.custom_url)
                else:
                    url = change_url(website)
                    link = '<br>Related website: <a href="%s">%s</a>' % (url, website.name)
                self.fields['custom_url'].help_text += link
        else:
            site_domain = self.plugin.site_domain
        context = {
            'site_name': '&lt;site_name&gt;',
            'name': '&lt;site_name&gt;',
        }
        site_domain = site_domain % context
        if '&lt;site_name&gt;' in site_domain:
            site_link = site_domain
        else:
            site_link = '<a href="http://%s">%s</a>' % (site_domain, site_domain)
        self.fields['site_url'].widget.display = site_link
        self.fields['name'].label = _("Site name") if '%(' in self.plugin.site_domain else _("Username")

def display_url(self, saas):
        site_domain = saas.get_site_domain()
        site_link = '<a href="http://%s">%s</a>' % (site_domain, site_domain)
        links = [site_link]
        if saas.custom_url and isinstalled('orchestra.contrib.websites'):
            try:
                website = saas.service_instance.get_website()
            except ObjectDoesNotExist:
                warning = _("Related website directive does not exist for this custom URL.")
                link = '<span title="%s" style="color:red">%s</span>' % (warning, saas.custom_url)
            else:
                website_link = get_on_site_link(saas.custom_url)
                admin_url = change_url(website)
                link = '<a href="%s" title="Edit website">%s %s</a>' % (
                    admin_url, saas.custom_url, website_link
                )
            links.append(link)
        return '<br>'.join(links)
    display_url.short_description = _("URL")