If you only see it once, sure. But if you use it as an idiom, it will be clearer once you do know what it does. Similarly, flatten( my_list_of_lists ) is MUCH

If you only see it once, sure. But if you use it as an idiom, it will be clearer once you do know what it does. Similarly, flatten( my_list_of_lists ) is MUCH easier to read than the construct that you end up writing to flatten a list of lists.