High Order Messages in Python

[vdrab]

On a (somewhat) related note,
I've always wondered whether it is possible to emulate ruby blocks
using a python generator '+ alpha'. In my limited understanding of the
ruby block, the generator can inject values into a block, I suppose,
but what is the block itself? can it be a function? a class instance?
what would it look like? I am sure someone must have played around with
this. 
any pointers?
cheers,
v.