              if node.obj is obj:
                  node.key = new_key
                  return node
          return None
 
</s> remove         return None </s> add  </s> remove    "execution_count": null,
   "metadata": {
    "collapsed": false
   },
 </s> add    "execution_count": 1,
   "metadata": {}, </s> remove     "This notebook was prepared by [hashhar](https://github.com/hashhar), second solution added by [janhak] (https://github.com/janhak). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
 </s> add     "This notebook was prepared by [hashhar](https://github.com/hashhar), second solution added by [janhak](https://github.com/janhak). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)." </s> remove     main() </s> add 
        return None
              if node.obj is obj:
                  node.key = new_key
                  return node
          return None
        return None
keep keep keep add
 #273: Remove nose dependency for arrays_strings/ (#274) 
arrays_strings/priority_queue/priority_queue.py