Section 9.14 Cloning Lists
If we want to modify a list and also keep a copy of the original, we need to be able to make a copy of the list itself, not just the reference. This process is sometimes called cloning, to avoid the ambiguity of the word copy.
The easiest way to clone a list is to use the slice operator.
Taking any slice of a list creates a new list. In this case the slice happens to consist of the whole list. (Remember that leaving off the number before the
: starts at the first element, and leaving off the second number ends at the last element. When you omit both numbers, you get the entire list.)Now we are free to make changes to
b without worrying about a. Again, we can see in codelens that a and b are entirely different list objects.
