<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_publish_path(self, obj):
 """ publish_path joins the publish_paths for the chat type and the channel. """

        return os.path.join(
            obj.chat_type.publish_path, obj.publish_path.lstrip("/")
        )