运行时，错误提示如下：

E:?[36mGRAPHOPT?[0m:fail to optimize the graph!
....
  File "/home/bonky/anaconda3/lib/site-packages/bert_serving/server/__init__.py", line 70, in __init__
    self.graph_path, self.bert_config = pool.apply(optimize_graph, (self.args,))
TypeError: cannot unpack non-iterable NoneType object


直接降级 bert-serving-server 到 1.8 版本即可运行

pip install -U bert-serving-server==1.8