Getting a path from a file object

[Andrew Fong]

Newbie question:

Let's say I open a new file for writing in a certain path. How do I
get that path back?

Example:

>>> f = open('/some/path/file.ext')
>>> some_function(f)
'/some/path/file.ext'

Does some_function(f) already exist? And if not, how would I define
it?

-- Andrew