[Tutor] Reset function

[Christopher Smith]

Dear tutor,

I looked at the reset function presented recently to "purify the namespace"
before running a program (reset(vars())) and the last line has me stumped.
 
Here's a simplified version: 

###
def reset(namespace, user_safe_items=()):
	for item in namespace.keys():
		exec "del "+item in namespace

###

I thought something like "del item";

or "del namespace[item]" might work (they don't).

What is the "item in namespace" doing??  Namespace isn't a sequence
so why does this even work?

Any help appreciated.

/c