code: def demo_login(self, auth=None, url=None):
          
          assert all([
              auth or url,  # Must provide at least one
              not (auth and url)  # Cannot provide more than one
          ])
          if url is None:
              url = "https://piazza.com/demo_login"
              params = dict(nid=self._nid, auth=auth)
              res = self.session.get(url, params=params)
          else:
              res = self.session.get(url)
docs: Authenticate with a "Share Your Class" URL using a demo user.
  
          You may provide either the entire ``url`` or simply the ``auth``
          parameter.
  
          :param url: Example - "https://piazza.com/demo_login?nid=hbj11a1gcvl1s6&auth=06c111b"
          :param auth: Example - "06c111b"