<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def task_queues(self):
 """ Access the task_queues :returns: twilio.rest.taskrouter.v1.workspace.task_queue.TaskQueueList :rtype: twilio.rest.taskrouter.v1.workspace.task_queue.TaskQueueList """

        if self._task_queues is None:
            self._task_queues = TaskQueueList(self._version, workspace_sid=self._solution['sid'], )
        return self._task_queues