How to use the cliboa.util.gcp.ServiceAccount.auth function in cliboa

def test_auth_no_credentials(self):
        assert ServiceAccount.auth(None) is None

is_inserted: if the data is already inserted or not
            if_exists: replace or append
        """
        df = pandas.DataFrame(self._format_insert_data(insert_rows))
        if is_inserted is True:
            # if_exists after the first insert execution
            if_exists = self._APPEND
        dest_tbl = self._dataset + "." + self._tblname
        self._logger.info("Start insert %s rows to %s" % (len(insert_rows), dest_tbl))
        df.to_gbq(
            dest_tbl,
            project_id=self._project_id,
            if_exists=if_exists,
            table_schema=self._table_schema,
            location=self._location,
            credentials=ServiceAccount.auth(self._credentials),
        )

def get_gcs_client(credentials):
        return storage.Client(credentials=ServiceAccount.auth(credentials))

def execute(self, *args):
        super().execute()
        valid = EssentialParameters(self.__class__.__name__, [self._key])
        valid()

        df = pandas.read_gbq(
            query=self._get_query(),
            dialect="standard",
            location=self._location,
            project_id=self._project_id,
            credentials=ServiceAccount.auth(self._credentials),
        )
        ObjectStore.put(self._key, df)

is_inserted: if the data is already inserted or not
            if_exists: replace or append
        """
        df = pandas.DataFrame(self.__format_insert_data(insert_rows))
        if is_inserted is True:
            # if_exists after the first insert execution
            if_exists = self.APPEND
        dest_tbl = self._dataset + "." + self._tblname
        self._logger.info("Start insert %s rows to %s" % (len(insert_rows), dest_tbl))
        df.to_gbq(
            dest_tbl,
            project_id=self._project_id,
            if_exists=if_exists,
            table_schema=self._table_schema,
            location=self._location,
            credentials=ServiceAccount.auth(self._credentials),
        )

def get_firestore_client(credentials):
        return firestore.Client(credentials=ServiceAccount.auth(credentials))

def _save_to_cache(self):
        self._logger.info("Save data to on memory")
        df = pandas.read_gbq(
            query="SELECT * FROM %s.%s" % (self._dataset, self._tblname)
            if self._query is None
            else self._query,
            dialect="standard",
            location=self._location,
            project_id=self._project_id,
            credentials=ServiceAccount.auth(self._credentials),
        )
        ObjectStore.put(self._key, df)

def get_bigquery_client(credentials):
        """
        get bigquery client object
        Args:
           credentials: gcp service account json
        """
        return bigquery.Client(credentials=ServiceAccount.auth(credentials))