code: def session(self):
          
          if self._session is None:
              self._session = requests.session()
              self._session.headers.update(
                  {
                      "Authorization": "Bearer {}".format(self.token),
                      "User-Agent": "ads-api-client/{}".format(__version__),
                      "Content-Type": "application/json",
                  }
              )
          return self._session
docs: http session interface, transparent proxy to requests.session