Clearing a list in place will affect all other references of the same list.

For example, this method doesn't affect other references:

>>> a = [1, 2, 3] >>> b = a >>> a = [] >>> print(a) [] >>> print(b) [1, 2, 3]

But this one does:

>>> a = [1, 2, 3] >>> b = a >>> del a[:] # equivalent to del a[0:len(a)] >>> print(a) [] >>> print(b) [] >>> a is b True

You could also do:

>>> a[:] = []


으아아!