[anaphor]

Wrong. You only need to use the free variables of the closure, you don't need to copy the entire environment from the function you're defining your closure in. By the definition of a free variable you actually use it, otherwise it wouldn't be a free variable of the function! Python definitely does not work the same way, but in Python "x = 3" can inadvertently shadow (make a local name) something defined in the outer scope, but that's a completely different problem.