docs: def to_url(self):
          """Serialize as a URL for a GET request."""
          base_url = urlparse(self.url)
  
          query = parse_qs(base_url.query)
          for k, v in self.items():
              query.setdefault(k, []).append(to_utf8_optional_iterator(v))
          scheme = base_url.scheme
          netloc = base_url.netloc
          path = base_url.path
          params = base_url.params
          fragment = base_url.fragment
  
          url = (scheme, netloc, path, params, urlencode(query, True), fragment)
          return urlunparse(url)