python 3: sorting with a comparison function

[Thomas Heller]

bearophileHUGS at lycos.com schrieb:
> Kay Schluehr:
>> Sometimes it helps when people just make clear how they use technical
>> terms instead of invoking vague associations.
> 
> And generally Python docs can enjoy growing few thousands examples...

Well, that may not be necessary.  But I think that a clear example how to use
the 'key=' parameter in the sort() and sorted() method/function is badly needed.

Thomas