How to use the pretix.multidomain.urlreverse.eventreverse function in pretix

def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['subevent'] = self.subevent
        context['cart_redirect'] = eventreverse(self.request.event, 'presale:event.checkout.start',
                                                kwargs={'cart_namespace': kwargs.get('cart_namespace') or ''})
        if context['cart_redirect'].startswith('https:'):
            context['cart_redirect'] = '/' + context['cart_redirect'].split('/', 3)[3]
        return context

context['items_by_category'] = item_group_by_category(items)

        context['subevent'] = self.subevent
        context['seating_available'] = self.voucher.seating_available(self.subevent)

        context['new_tab'] = (
            'require_cookie' in self.request.GET and
            settings.SESSION_COOKIE_NAME not in self.request.COOKIES
            # Cookies are not supported! Lets just make the form open in a new tab
        )

        if self.request.event.settings.redirect_to_checkout_directly:
            context['cart_redirect'] = eventreverse(self.request.event, 'presale:event.checkout.start',
                                                    kwargs={'cart_namespace': kwargs.get('cart_namespace') or ''})
        else:
            context['cart_redirect'] = eventreverse(self.request.event, 'presale:event.index',
                                                    kwargs={'cart_namespace': kwargs.get('cart_namespace') or ''})
        if context['cart_redirect'].startswith('https:'):
            context['cart_redirect'] = '/' + context['cart_redirect'].split('/', 3)[3]

        return context

first = d == date_from
                ebd[d].append({
                    'continued': not first,
                    'timezone': settings.timezone,
                    'time': datetime_from.time().replace(tzinfo=None) if first and settings.show_times else None,
                    'event': se,
                    'url': eventreverse(se.event, 'presale:event.index', kwargs=kwargs)
                })
                d += timedelta(days=1)

        else:
            ebd[date_from].append({
                'event': se,
                'continued': False,
                'time': datetime_from.time().replace(tzinfo=None) if se.event.settings.show_times else None,
                'url': eventreverse(se.event, 'presale:event.index', kwargs=kwargs),
                'timezone': se.event.settings.timezone,
            })

def get_index_url(self):
        kwargs = {}
        if 'cart_namespace' in self.kwargs:
            kwargs['cart_namespace'] = self.kwargs['cart_namespace']
        return eventreverse(self.request.event, 'presale:event.index', kwargs=kwargs)

def get_order_url(self):
        return eventreverse(self.request.event, 'presale:event.order', kwargs={
            'order': self.order.code,
            'secret': self.order.secret
        })

def get(self, request, *args, **kwargs):
        from pretix.presale.views.cart import get_or_create_cart_id

        self.subevent = None
        if request.GET.get('src', '') == 'widget' and 'take_cart_id' in request.GET:
            # User has clicked "Open in a new tab" link in widget
            get_or_create_cart_id(request)
            return redirect(eventreverse(request.event, 'presale:event.index', kwargs=kwargs))
        elif request.GET.get('iframe', '') == '1' and 'take_cart_id' in request.GET:
            # Widget just opened, a cart already exists. Let's to a stupid redirect to check if cookies are disabled
            get_or_create_cart_id(request)
            return redirect(eventreverse(request.event, 'presale:event.index', kwargs=kwargs) + '?require_cookie=true&cart_id={}'.format(
                request.GET.get('take_cart_id')
            ))
        elif request.GET.get('iframe', '') == '1' and len(self.request.GET.get('widget_data', '{}')) > 3:
            # We've been passed data from a widget, we need to create a cart session to store it.
            get_or_create_cart_id(request)
        elif 'require_cookie' in request.GET and settings.SESSION_COOKIE_NAME not in request.COOKIES:
            # Cookies are in fact not supported
            r = render(request, 'pretixpresale/event/cookies.html', {
                'url': eventreverse(
                    request.event, "presale:event.index", kwargs={'cart_namespace': kwargs.get('cart_namespace') or ''}
                ) + (
                    "?src=widget&take_cart_id={}".format(request.GET.get('cart_id'))

try:
                resp = prov.execute_payment(request, payment)
            except PaymentException as e:
                messages.error(request, str(e))
                urlkwargs['step'] = 'payment'
                return redirect(eventreverse(request.event, 'presale:event.checkout', kwargs=urlkwargs))
            if resp:
                return resp
    else:
        messages.error(request, _('Invalid response from PayPal received.'))
        logger.error('Session did not contain payment_paypal_id')
        urlkwargs['step'] = 'payment'
        return redirect(eventreverse(request.event, 'presale:event.checkout', kwargs=urlkwargs))

    if payment:
        return redirect(eventreverse(request.event, 'presale:event.order', kwargs={
            'order': payment.order.code,
            'secret': payment.order.secret
        }) + ('?paid=yes' if payment.order.status == Order.STATUS_PAID else ''))
    else:
        urlkwargs['step'] = 'confirm'
        return redirect(eventreverse(request.event, 'presale:event.checkout', kwargs=urlkwargs))

def get(self, request, *args, **kwargs):
        from pretix.presale.views.cart import get_or_create_cart_id

        self.subevent = None
        if request.GET.get('src', '') == 'widget' and 'take_cart_id' in request.GET:
            # User has clicked "Open in a new tab" link in widget
            get_or_create_cart_id(request)
            return redirect(eventreverse(request.event, 'presale:event.seatingplan', kwargs=kwargs))
        elif request.GET.get('iframe', '') == '1' and 'take_cart_id' in request.GET:
            # Widget just opened, a cart already exists. Let's to a stupid redirect to check if cookies are disabled
            get_or_create_cart_id(request)
            return redirect(eventreverse(request.event, 'presale:event.seatingplan', kwargs=kwargs) + '?require_cookie=true&cart_id={}'.format(
                request.GET.get('take_cart_id')
            ))
        elif request.GET.get('iframe', '') == '1' and len(self.request.GET.get('widget_data', '{}')) > 3:
            # We've been passed data from a widget, we need to create a cart session to store it.
            get_or_create_cart_id(request)

        if request.event.has_subevents:
            if 'subevent' in kwargs:
                self.subevent = request.event.subevents.using(settings.DATABASE_REPLICA).filter(pk=kwargs['subevent'], active=True).first()
                if not self.subevent or not self.subevent.seating_plan:
                    raise Http404()
                return super().get(request, *args, **kwargs)

def frontend_file_url(self):
        from pretix.multidomain.urlreverse import eventreverse

        if self.file:
            if self.orderposition:
                url = eventreverse(self.orderposition.order.event, 'presale:event.order.download.answer', kwargs={
                    'order': self.orderposition.order.code,
                    'secret': self.orderposition.order.secret,
                    'answer': self.pk,
                })
            else:
                url = eventreverse(self.cartposition.event, 'presale:event.cart.download.answer', kwargs={
                    'answer': self.pk,
                })

            return url
        return ""

def get_next_url(self):
        if "next" in self.request.GET and is_safe_url(self.request.GET.get("next"), allowed_hosts=None):
            u = self.request.GET.get('next')
        else:
            kwargs = {}
            if 'cart_namespace' in self.kwargs:
                kwargs['cart_namespace'] = self.kwargs['cart_namespace']
            u = eventreverse(self.request.event, 'presale:event.index', kwargs=kwargs)
        if '?' in u:
            u += '&require_cookie=true'
        else:
            u += '?require_cookie=true'
        disclose_cart_id = (
            'iframe' in self.request.GET or settings.SESSION_COOKIE_NAME not in self.request.COOKIES
        ) and self.kwargs.get('cart_namespace')
        if disclose_cart_id:
            cart_id = get_or_create_cart_id(self.request)
            u += '&cart_id={}'.format(cart_id)
        return u