How to empty a list?

This actually removes the contents from the list, but doesn’t replace the old label with a new empty list:

del lst[:]

Here’s an example:

lst1 = [1, 2, 3]
lst2 = lst1
del lst1[:]
print(lst2)

For the sake of completeness, the slice assignment has the same effect:

lst[:] = []

It can also be used to shrink a part of the list while replacing a part at the same time (but that is out of the scope of the question).

Note that doing lst = [] does not empty the list, just creates a new object and binds it to the variable lst, but the old list will still have the same elements, and effect will be apparent if it had other variable bindings.

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