def __init__(self):
    self.word2idx = {WORD[PAD]: PAD, WORD[UNK]: UNK, WORD[BOS]: BOS, WORD[EOS]: EOS}
    self.idx = len(self.word2idx)
def __init__(self):
    self.word2idx = {WORD[PAD]: PAD, WORD[UNK]: UNK, WORD[BOS]: BOS, WORD[EOS]: EOS}
    self.idx = len(self.word2idx)