Running the NLI example

[EricXQiu]

Hi OpenAttack Team,

I am running the NLI example code in colab but get a URL error: The example code is in https://github.com/thunlp/OpenAttack/blob/master/examples/nli_attack.py

To be specific, it is this line that causes the problem:

attacker = OpenAttack.attackers.PWWSAttacker()

---------------------------------------------------------------------------
SSLCertVerificationError                  Traceback (most recent call last)
/usr/lib/python3.7/urllib/request.py in do_open(self, http_class, req, **http_conn_args)
   1349                 h.request(req.get_method(), req.selector, req.data, headers,
-> 1350                           encode_chunked=req.has_header('Transfer-encoding'))
   1351             except OSError as err: # timeout error

22 frames
SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1091)

During handling of the above exception, another exception occurred:

URLError                                  Traceback (most recent call last)
/usr/lib/python3.7/urllib/request.py in do_open(self, http_class, req, **http_conn_args)
   1350                           encode_chunked=req.has_header('Transfer-encoding'))
   1351             except OSError as err: # timeout error
-> 1352                 raise URLError(err)
   1353             r = h.getresponse()
   1354         except:

URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1091)>

Could you help me with it?