def example():
    x = np.random.randn(10, 10)
    y = np.asarray(
        [
            [0.8, 0.4],
            [0.4, 0.3],
            [0.34, 0.45],
            [0.67, 0.32],
            [0.88, 0.67],
            [0.78, 0.77],
            [0.55, 0.66],
            [0.55, 0.43],
            [0.54, 0.1],
            [0.1, 0.5],
        ]
    )
    model = BPNN()
    for i in (10, 20, 30, 2):
        model.add_layer(DenseLayer(i))
    model.build()
    model.summary()
    model.train(xdata=x, ydata=y, train_round=100, accuracy=0.01)