Does Python set update() replace existing items?

Question

If I use my_set.update(my_list) where some elements of my_list are == existing elements in my_set, does it replace the existing items or not?

Answer 1

It does not replace existing elements, as can be seen from the following example:

>>> s = {1}
>>> s.add(1.0)
>>> s
{1}

The same behavior holds for dictionary keys:

>>> d = {1: 'foo'}
>>> d.update({1.0: 'bar'})
>>> d
{1: 'bar'}