python3: 'where' keyword

[Andrey Tatarinov]

Bengt Richter wrote:
>>>It also allows the necessary but uninteresting setup for an expression 
>>>to be moved "out of the way", bringing the expression that does the real 
>>>work to prominence.
>>Killer app for this keyword:
>>
>>class C(object):
>>
>>  x = property(get, set) where:
>>    def get(self):
>>      return "Silly property"
>>    def set(self, val):
>>      self.x = "Told you it was silly"
> Yes, that is cool and it _is_ an interesting idea. Are suites nestable? E.g., is this legal?
...
> And, is the whole thing after the '=' an expression? E.g.,
> 
>   x = ( foo(x) where:
>          x = math.pi/4.0
>       ) where:
>          def foo(x): print 'just for illustration', x
> 
> or is this legal?
> 
>   for y in ([foo(x) for x in bar] where:
>                  bar = xrange(5)
>             ): baz(y) where:
>                 def baz(arg): return arg*2
> 
> Not trying to sabotage the idea, really, just looking for clarification ;-)

yes, all your examples are correct. And that's the way I'd like to use 
this feature.