Running clean-up code with finally

Sometimes, you may want something to occur regardless of whatever exception happened, for example, if you have to clean up some resources.

The finally block of a try clause will happen regardless of whether any exceptions were raised.

resource = allocate_some_expensive_resource()
try:
    do_stuff(resource)
except SomeException as e:
    log_error(e)
    raise  # re-raise the error
finally:
    free_expensive_resource(resource)

This pattern is often better handled with context managers (using the with statement).