Something in the function tutorial confused me.

[Lee Fleming]

On Aug 6, 12:30 pm, "Hamilton, William " <wham... at entergy.com> wrote:
> When you call f(23), the variable y within it gets created and points at
> None.  When f(23) exits, the y that it created gets destroyed.  (Well,
> goes out of scope, but even if it's not garbage collected it won't ever
> come back into scope.)  When you then call f(24), a new y is created
> that also points to None, and disappears forever when f(24) exits.
>
> The values in a def statement are created when the def is executed, but
> the variables are only created when the function is actually called, and
> new ones are created every time the function is called.
>
> --
> -Bill Hamilton- Hide quoted text -
>
> - Show quoted text -

why isn't the y in def f (x, y = []): something
garbage-collected?