docs: def walk(zk, path='/'):
      """Yields all paths under `path`."""
      children = zk.get_children(path)
      yield path
      for child in children:
          if path == '/':
              subpath = "/%s" % child
          else:
              subpath = "%s/%s" % (path, child)
  
          for child in walk(zk, subpath):
              yield child