JSONDecodeError

1. 使用ptyhon第三方库stanfordcorenlp中pos_tag()方法时，%（百分号）导致JSONDecodeError。

   print(nlp.pos_tag('this is a apple'))  # [('this', 'DT'), ('is', 'VBZ'), ('a', 'DT'), ('apple', 'NN')]
   print(nlp.pos_tag('this is a %'))
   
   JSONDecodeError                           Traceback (most recent call last)
   <ipython-input-83-4a86c2360061> in <module>
   ----> 1 nlp.pos_tag('this is a %')
   
   c:\users\luyiheng\anaconda3\lib\site-packages\stanfordcorenlp\corenlp.py in pos_tag(self, sentence)
     183 
     184     def pos_tag(self, sentence):
   --> 185         r_dict = self._request('pos', sentence)
     186         words = []
     187         tags = []
   
   c:\users\luyiheng\anaconda3\lib\site-packages\stanfordcorenlp\corenlp.py in _request(self, annotators, data, *args, **kwargs)
     237         logging.info(params)
     238         r = requests.post(self.url, params=params, data=data, headers={'Connection': 'close'})
   --> 239         r_dict = json.loads(r.text)
     240 
     241         return r_dict
   
   c:\users\luyiheng\anaconda3\lib\json\__init__.py in loads(s, encoding, cls, object_hook, parse_float, parse_int, parse_constant, object_pairs_hook, **kw)
     317             parse_int is None and parse_float is None and
     318             parse_constant is None and object_pairs_hook is None and not kw):
   --> 319         return _default_decoder.decode(s)
     320     if cls is None:
     321         cls = JSONDecoder
   
   c:\users\luyiheng\anaconda3\lib\json\decoder.py in decode(self, s, _w)
     337 
     338         """
   --> 339         obj, end = self.raw_decode(s, idx=_w(s, 0).end())
     340         end = _w(s, end).end()
     341         if end != len(s):
   
   c:\users\luyiheng\anaconda3\lib\json\decoder.py in raw_decode(self, s, idx)
     355             obj, end = self.scan_once(s, idx)
     356         except StopIteration as err:
   --> 357             raise JSONDecodeError("Expecting value", s, err.value) from None
     358         return obj, end
   
   JSONDecodeError: Expecting value: line 1 column 1 (char 0)