code: def get_headers(self, session, **kwargs):
          
  
          if self.auth_token is None:
              try:
                  self._refresh_tokens(session)
                  self._fetch_credentials(session)
              except:
                  raise AuthorizationFailure()
  
          return {
              'X-Auth-Token': self.auth_token,
          }
docs: Get the authentication header.
  
          If the current session has not been authenticated, this will trigger a
          new authentication to the HubiC OAuth service.
  
          :param keystoneclient.Session session: The session object to use for
                                                 queries.
  
          :raises keystoneclient.exceptions.AuthorizationFailure: if something
                                                                  goes wrong.
  
          :returns: The headers used for authenticating requests.
          :rtype: dict