String to valid Python identifier

["Martin v. Löwis"]

> Is there any easy function in the stdlib to convert any random string in 
> a valid Python identifier .. possibly by replacing non-valid characters 
> with _ ?

I think this is fairly underspecified as a problem statement. A solution
that would meet your specification would be

def mkident(s):
    return "foo"

It returns a valid Python identifier for any random string.

If you now complain that this gives too many collisions, I propose

def mkident(s):
    return "foo%d" % (hash(s) & 0x7fffffff)

Regards,
Martin