code: def build_url_request(self):
          
          params = {}
          headers = {}
          self._authenticator(params, headers)
          self._grant(params)
          return Request(self._endpoint, urlencode(params), headers)
docs: Consults the authenticator and grant for HTTP request parameters and
          headers to send with the access token request, builds the request using
          the stored endpoint and returns it.