If I need to change a type thats passed to a function that already exists and is heavily used, I would either cast the old type to the new type so both work, o

If I need to change a type thats passed to a function that already exists and is heavily used, I would either cast the old type to the new type so both work, or create a new function. If I really cared about cleaning it up I would add a deprecation warning when its done the old way.