ion=&#34;softmax&#34;,
    metrics=[&#34;accuracy&#34;],
    verbose=1,
):
    model = keras.models.Sequential()
    model.add(keras.layers.Embedding(max_features, 256, input_length=maxlen))
    model.add(keras.layers.GRU(256, dropout=0.9, return_sequences=True))
    model.add(keras.layers.GRU(256, dropout=0.9))
    model.add(keras.layers.Dense(num_classes, activation=activation))
    model.compile(loss=loss_func, optimizer=U.DEFAULT_OPT, metrics=metrics)
    return model


def _build_bigru(
    num_classes