content: https://github.com/OpenNMT/OpenNMT-py.git
  
  # Additional Components: 
  
  1.BPE/ Word-piece
  https://github.com/rsennrich/subword-nmt
  减少未登录词（OOV）的问题
  
  onmt/transforms
  - tokenize.py
  class BPETransform(TokenizerTransform):
  - transform.py
  class TransformPipe(Transform):
  <-
  inference_engine.py:class InferenceEngineCT2(InferenceEngine):self.transform.apply_reverse(tokens)
  
  2.Shared Embeddings
  https://arxiv.org/abs/1608.05859
  
  share_embeddings参数
  onmt/model_builder.py
  
  3.Beam Search
  https://github.com/OpenNMT/OpenNMT-py/
  
  4.Model Averaging
  