Flexible string representation, unicode, typography, ...

[Roy Smith]

In article <503f8e33$0$30001$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> On Thu, 30 Aug 2012 07:02:24 -0400, Roy Smith wrote:
> > Is the implementation smart enough to know that x == y is always False
> > if x and y are using different internal representations?
> 
> [...] There may be circumstances where two strings have different 
> internal representations even though their content is the same

If there is a deterministic algorithm which maps string content to 
representation type, then I don't see how it's possible for two strings 
with different representation types to have the same content.  Could you 
give me an example of when this might happen?