@staticmethod
    def _is_gcs_s3(user_id):
        return len(user_id) == 20 and user_id.startswith('GOOG')
Checks S3 key format: 20 alphanumeric chars starting with GOOG.
dataset/ETHPy150Open apache/libcloud/libcloud/common/google.py/GoogleAuthType._is_gcs_s3