When passing an object using the copy operator, will all nested structures inside it be transferred?

When copying an object in Python using the assignment operator (=), a new reference to the same object is created, not a copy. However, if you use the copy module and the copy.copy() function, a shallow copy is created — the object itself is copied, but nested objects (for example, lists inside the object) remain references to the originals.

To copy an object along with all its nested structures (deep copying), you should use copy.deepcopy(). This creates a completely independent copy of the object and all objects nested within it.

Example:

import copy

original = {'a': [1, 2, 3]}
shallow_copy = copy.copy(original)
deep_copy = copy.deepcopy(original)

shallow_copy['a'].append(4)
print(original['a'])  # Outputs [1, 2, 3, 4] — the nested list has changed

deep_copy['a'].append(5)
print(original['a'])  # Outputs [1, 2, 3, 4] — the original remains unchanged

Thus, with the assignment operator (=) or shallow copying, nested structures are not copied, but with deep copying, they are copied.