- def shallowfy(lista): 
-       shallow = [] 
-       for el in lista: 
-         if (isinstance(el, list)): 
-           shallow_el = shallowfy(el) 
-           for subel in shallow_el: 
-             shallow.append(subel) 
-         else: 
-           shallow.append(el) 
-       return shallow 
-   
- print(shallowfy([1, 2, [[[3, [4], 5, [6, 7, [[8, 9], 10, [11]], 12], 13], 14], 15], 16, [17, [[[18]]], 19], 20])) 
- print(shallowfy([[1, 2], [3, 4, 5], [], [6, 7]])) 
-   
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		[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
[1, 2, 3, 4, 5, 6, 7]