We have a tuple where all elements are lists. If one of the lists is modified (append), will the tuple change?

A tuple in Python is an immutable data type, meaning the tuple itself cannot be changed after creation: elements cannot be added, removed, or replaced.

However, if the elements of the tuple are mutable objects, such as lists, then the contents of those lists can be changed. Modifying the contents of a list inside a tuple does not change the tuple object itself, but it does change the data inside the mutable element.

Example:

t = ([1, 2], [3, 4])
t[0].append(5)
print(t)  # Outputs: ([1, 2, 5], [3, 4])

Thus, the tuple as an object remains unchanged (its structure and references to objects are the same), but the contents of the nested list have changed. It is important to understand this distinction to avoid confusing the immutability of the container with the mutability of its elements.