Favorite non-python language trick?

[Rocco Moretti]

Jp Calderone wrote:
> On Fri, 01 Jul 2005 15:02:10 -0500, Rocco Moretti 
> <roccomoretti at hotpop.com> wrote:
> 
>>
>> I'm not aware of a language that allows it, but recently I've found
>> myself wanting the ability to transparently replace objects. 
> 
> 
> Smalltalk supports this with the "become" message.  I have also done an 
> implementation of this for Python.

As a pure Python module, or do you have to recompile the interpreter?