Callable assertion?

[Roy Smith]

In article <wMOdnYxfQN0hux2iRTvUqg at speakeasy.net>,
 "A.M. Kuchling" <amk at amk.ca> wrote:

> On Sun, 05 Oct 2003 08:55:45 -0400, 
> 	Roy Smith <roy at panix.com> wrote:
> > the right thing to do, or is there something cleaner?  Will that work 
> > for all callable values of param, regardless if it's a static function, 
> > class method, built-in, etc?
> 
> There's a callable(param) built-in function, dating back to Python 1.2.
> 
> --amk

Ah.  That's exactly what I was looking for!  The docs say:

"Return true if the object argument appears callable, false if not.  If 
this returns true, it is still possible that a call fails,  but if it is 
false, calling object will never succeed."

What does "appears callable" mean?  Under what circumstances would 
callable(foo) return True, yet foo() would fail?