import tensorflow as tf

    constructing a BidirectionalLanguageModel.
    '''
    with open(options_file, 'r') as fin:
        options = json.load(fin)
    max_word_length = options['char_cnn']['max_characters_per_token']

    vocab = UnicodeCharsVocabulary(vocab_file, max_word_length)
    batcher = Batcher(vocab_file, max_word_length)

    ids_placeholder = tf.placeholder('int32',
                                     shape=(None, None, max_word_length)
    )
    model = BidirectionalLanguageModel(options_file, weight_file)
    embedding_op = model(ids_placeholder)['token_embeddings']

    n_tokens = vocab.size
    embed_dim = int(embedding_op.shape[2])

