Python "property object has no attribute" Exception

Question

confirmation = property(_get_confirmation, _set_confirmation)
confirmation.short_description = "Confirmation"

When I try the above I get an Exception I don't quite understand:

AttributeError: 'property' object has no attribute 'short_description'

This was an answer to another question on here but I couldn't comment on it as I don't have enough points or something. :-(

In other tests I've also got this error under similar circumstances:

TypeError: 'property' object has only read-only attributes (assign to .short_description)

Any ideas anybody?