Python List Copying with Slice Notation

In Python, the [:] slice notation can be used to create a shallow copy of a sequence.

my_list = [1, 2, 3]
copy_list = my_list[:]
assert not my_list is copy_list

For mutable sequences (like lists):

[:] creates a new object (different id())
but the contents (the elements inside) are still the same objects as in the original list (shallow copy).

For immutable sequences (like strings or tuples):

Slicing with [:] does not create a new object.
The original object is returned because immutability makes copying unnecessary.

my_str = "hello"
assert my_str[:] is my_str

my_tuple = (1, 2, 3)
assert my_tuple[:] is my_tuple

Nested structures

[:] only creates a shallow copy. If the original list contains other mutable objects (lists, dicts, etc.), both copies will still reference the same inner objects.
my_list = [[1], [2]]
copy_list = my_list[:]
copy_list[0][0] = 99
assert my_list == [[99], [2]]
assert not my_list is [[99], [2]]