code: def default_redirect(request, fallback_url, **kwargs):
      
      redirect_field_name = kwargs.get("redirect_field_name", "next")
      next = request.POST.get(redirect_field_name,
                              request.GET.get(redirect_field_name, ''))
      if not next:
          # try the session if available
          if hasattr(request, "session"):
              session_key_value = kwargs.get("session_key_value", "redirect_to")
              next = request.session.get(session_key_value)
      is_safe = functools.partial(
          ensure_safe_url,
          allowed_protocols=kwargs.get("allowed_protocols"),
          allowed_host=request.get_host()
      )
      redirect_to = next if next and is_safe(next) else fallback_url
      # perform one last check to ensure the URL is safe to redirect to. if it
      # is not then we should bail here as it is likely developer error and
      # they should be notified
      is_safe(redirect_to, raise_on_fail=True)
      return redirect_to
docs: Evaluates a redirect url by consulting GET, POST and the session.