def get_client_secret(self, client_key, request):
        log.debug('Get client secret of %r', client_key)
        if not request.client:
            request.client = self._clientgetter(client_key=client_key)
        if request.client:
            return request.client.client_secret
        return None
make sure multiple series can be added
dataset/ETHPy150Open lepture/flask-oauthlib/flask_oauthlib/provider/oauth1.py/OAuth1RequestValidator.get_client_secret--crossover with--dataset/ETHPy150Open unbracketed/python-flot-utils/pyflot/tests/__init__.py/TestFlot.test_add_multiple_series