Can't get root keys about python-etcd HOT 5 CLOSED

>>> c.set('/a/b/c', 5)
EtcdResult(action=u'SET', index=17, key=u'/a/b/c', prevValue=u'5', value=u'5', expiration=None, ttl=None, newKey=None)

>>> c.get('/a/b/c')
EtcdResult(action=u'GET', index=17, key=u'/a/b/c', prevValue=None, value=u'5', expiration=None, ttl=None, newKey=None)

>>> c.get('/a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/etcd/client.py", line 285, in get
    return self._result_from_response(response)
  File "/Library/Python/2.7/site-packages/etcd/client.py", line 327, in _result_from_response
    raise etcd.EtcdException('Unable to decode server response')
etcd.EtcdException: Unable to decode server response

>>> c.get('/a/b')
[EtcdResult(action=u'GET', index=17, key=u'/a/b/c', prevValue=None, value=u'5', expiration=None, ttl=None, newKey=None)]

>>> c.get('/')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/etcd/client.py", line 285, in get
    return self._result_from_response(response)
  File "/Library/Python/2.7/site-packages/etcd/client.py", line 327, in _result_from_response
    raise etcd.EtcdException('Unable to decode server response')
etcd.EtcdException: Unable to decode server response