def METHOD_NAME():
    # When all voxels are labeled
    img = np.ones((10, 10, 10))
    labels = np.ones((10, 10, 10))
    # It returns same labels which are provided
    pass_through = _random_walker(img, labels)
    np.testing.assert_array_equal(pass_through, labels)
    # When there is no seed
    # Case 1: only masked pixels
    labels = -np.ones((10, 10, 10))
    # It returns the labels
    np.testing.assert_array_equal(_random_walker(img, labels), labels)
    # Case 2: only unlabeled pixels
    labels = np.zeros((10, 10, 10))
    # It return the labels
    np.testing.assert_array_equal(_random_walker(img, labels), labels)