""" Copying """ a = [[1, 2], ["str", "str"]] b = a.copy() b[0].append(3) # print(a) # print(b) print(b[0] is a[0])

This code uses the .copy() method, which creates a shallow copy of the list a. This means that the outer list is copied, but the nested objects (inner lists) remain shared between both variables.

Example:

a = [[1, 2], ["str", "str"]]
b = a.copy()
b[0].append(3)

print(a)  # [[1, 2, 3], ['str', 'str']]
print(b)  # [[1, 2, 3], ['str', 'str']]
print(b[0] is a[0])  # True

Here, it is clear that modifying b[0] also affects a[0], since they are the same object. Therefore, b[0] is a[0] returns True.

If a deep copy is needed, where nested objects are also copied, you should use copy.deepcopy() from the copy module.