加密时出现
File "/usr/local/lib/python3.6/dist-packages/Charm_Crypto-0.50-py3.6-linux-x86_64.egg/charm/toolbox/policytree.py", line 46, in getBNF
OperatorOR = Literal("OR").setParseAction(downcaseTokens) | Literal("or")
NameError: name 'downcaseTokens' is not defined
怎么解决