code: def zk_client(host, scheme, credential):
      
  
      if not re.match(r".*:\d+$", host):
          host = "%s:%d" % (host, DEFAULT_ZK_PORT)
  
      client = KazooClient(hosts=host)
      client.start()
  
      if scheme != "":
          client.add_auth(scheme, credential)
  
      return client
docs: returns a connected (and possibly authenticated) ZK client