def METHOD_NAME():
    np.testing.assert_array_equal(
        normalization.ensure_grayscale(tf.ones([2, 2, 3], tf.uint8) * 255),
        tf.ones([2, 2, 1], tf.uint8) * 255,
    )
    np.testing.assert_array_equal(
        normalization.ensure_grayscale(tf.ones([2, 2, 1], tf.uint8) * 255),
        tf.ones([2, 2, 1], tf.uint8) * 255,
    )
    np.testing.assert_allclose(
        normalization.ensure_grayscale(tf.ones([2, 2, 3], tf.float32)),
        tf.ones([2, 2, 1], tf.float32),
        atol=1e-4,
    )