[Python-Dev] Proper tail recursion

[Andrew Koenig]

> Just a note: because Python sticks an implicit 'return None' at the end of
> a function, rather than returning the result of the last expression, like
> Scheme, you have to have an explicit return to see any effect:
> 
>  	def traverse(t, f):
>  		if t:
>  			f(t)
>  			traverse(t.left)
>  			return traverse(t.right)

Right.  I actually worked that out for myself not too long ago, and then
forgot it.