rm useless init_hidden in BiLSTM_CRF (pytorch#90)

Author: cmusjtuliuyuan

beginner_source/nlp/advanced_tutorial.py

@@ -277,14 +277,12 @@ def _viterbi_decode(self, feats):
         return path_score, best_path
 
     def neg_log_likelihood(self, sentence, tags):
-        self.hidden = self.init_hidden()
         feats = self._get_lstm_features(sentence)
         forward_score = self._forward_alg(feats)
         gold_score = self._score_sentence(feats, tags)
         return forward_score - gold_score
 
     def forward(self, sentence):  # dont confuse this with _forward_alg above.
-        self.hidden = self.init_hidden()
         # Get the emission scores from the BiLSTM
         lstm_feats = self._get_lstm_features(sentence)