ers: use [-1, -2, -3, -4]
        bert_model(str): alias for transformer_model
        word_embedding_dim (int): word embedding dimensions.
        char_embedding_dim (int): character embedding dimensions.
        word_lstm_size (int): character LSTM feature extractor output dimensions.
        char_lstm_size (int): word tagger LSTM output dimensions.
        fc_dim (int): output fully-connected layer size.
        dropout (float): dropout rate.

        verbose (boolean): verbosity of output
    Return:
  