def _is_c2d_topic(split_topic_str):
    """
    Topics for c2d message are of the following format:
    devices/<deviceId>/messages/devicebound
    :param split_topic_str: The already split received topic string
    """
    if "messages/devicebound" in split_topic_str and len(split_topic_str) > 4:
        return True
    return False