def METHOD_NAME(self):
    l = (1, 2, 3)  # make sure merge_lists does not modify it # noqa: E741
    self.assertListEqual(list(l), util.merge_lists([l]))
    self.assertListEqual(list(l), util.merge_lists([l, l]))
    self.assertListEqual(list(l), util.merge_lists([l, l, l, l, l, l, l]))
    self.assertListEqual(list(l), util.merge_lists([[], l, l, []]))
    self.assertListEqual(list(l), util.merge_lists([[1, 2, 3], [1, 2], [1]]))
    self.assertListEqual(list(l), util.merge_lists([[1, 2, 3], [2, 3], [3]]))
    self.assertListEqual(list(l), util.merge_lists([[1], [1, 2], [1, 2, 3]]))
    self.assertListEqual(list(l), util.merge_lists([[3], [2, 3], [1, 2, 3]]))
    self.assertListEqual(
        [1, 2, 3, 4, 5, 6], util.merge_lists([[1, 2, 4, 6], [1, 2, 3, 4, 5]])
    )