def _refresh(self, http):
try:<EOL><INDENT>self._retrieve_info(http)<EOL>self.access_token, self.token_expiry = _metadata.get_token(<EOL>http, service_account=self.service_account_email)<EOL><DEDENT>except http_client.HTTPException as err:<EOL><INDENT>raise client.HttpAccessTokenRefreshError(str(err))<EOL><DEDENT>
Refreshes the access token.

        Skip all the storage hoops and just refresh using the API.

        Args:
            http: an object to be used to make HTTP requests.

        Raises:
            HttpAccessTokenRefreshError: When the refresh fails.