docs: def parse_url(request, url):
      """Parse url URL parameter."""
      try:
          validate = URLValidator()
          validate(url)
      except ValidationError:
          if url.startswith('/'):
              host = request.get_host()
              scheme = 'https' if request.is_secure() else 'http'
              url = '{scheme}://{host}{uri}'.format(scheme=scheme,
                                                    host=host,
                                                    uri=url)
          else:
              url = request.build_absolute_uri(reverse(url))
      return url