trying to remember how to do inline code "testing"

[Alex Hunsley]

I can remember Python having a feature which allowed you to add some 
simple tests to your code, something like adding console output to your 
actual python script, like so:


 >>> 1+1
2
 >>> 2*7
14


... then python would actually run these queries and check that the 
expected results occurred.
I can't find the docs for this feauture anywhere, but I'm certain I 
didn't imagine this one!
Can anyone give me a reference?

thanks,
Alex