def _weights(vgg_layers, layer, expected_layer_name):
    """ Return the weights and biases already trained by VGG
    """
    W = vgg_layers[0][layer][0][0][2][0][0]
    b = vgg_layers[0][layer][0][0][2][0][1]
    layer_name = vgg_layers[0][layer][0][0][0][0]
    assert layer_name == expected_layer_name
    return W, b.reshape(b.size)