def retrieve_scopes(self, http):
self._retrieve_scopes(http)<EOL>return self.scopes<EOL>
Retrieves the canonical list of scopes for this access token.

        Gets the scopes from the OAuth2 provider.

        Args:
            http: httplib2.Http, an http object to be used to make the refresh
                  request.

        Returns:
            A set of strings containing the canonical list of scopes.