docs: def update_subscription(request, ident):
      "Shows subscriptions options for a verified subscriber."
      
      try:
          subscription = Subscription.objects.get(ident=ident)
      except Subscription.DoesNotExist:
          return respond('overseer/invalid_subscription_token.html', {}, request)
  
      if request.POST:
          form = UpdateSubscriptionForm(request.POST, instance=subscription)
          if form.is_valid():
              if form.cleaned_data['unsubscribe']:
                  subscription.delete()
          
                  return respond('overseer/unsubscribe_confirmed.html', {
                      'email': subscription.email,
                  })
              else:
                  form.save()
  
              return HttpResponseRedirect(request.get_full_path())
      else:
          form = UpdateSubscriptionForm(instance=subscription)
          
      context = csrf(request)
      context.update({
          'form': form,
          'subscription': subscription,
          'service_list': Service.objects.all(),
      })
  
      return respond('overseer/update_subscription.html', context, request)