I don't quite understand what is happening in the below code. Is it creating a copy of a nested list? If so, how is it doing it? What is b equal to?
a = [[1,2,3],[4,5,6]]
b = [x[:] for x in a]
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1This is making a deep copy of the list. By default, l[:] is l[0:len(l)] – BlueSheepToken Apr 12 '19 at 21:34
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And [this post](https://stackoverflow.com/questions/240178/list-of-lists-changes-reflected-across-sublists-unexpectedly) explains why you may want to do this. – pault Apr 12 '19 at 21:36
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x[:] selects all items in list x, so you're selecting all indexes of list x for x in list a of x's – Akin Hwan Apr 12 '19 at 21:45