<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def destroy_walker(self, walker):
 """Destroy a previously created stream walker. Args: walker (StreamWalker):
 The walker to remove from internal updating lists. """


        if walker.buffered:
            self._queue_walkers.remove(walker)
        else:
            self._virtual_walkers.remove(walker)