For the record: on second reading, I should have said "that scope is bundled with nextcolor and returned as a closure", not "bound to nextcolor", since the word

For the record: on second reading, I should have said "that scope is bundled with nextcolor and returned as a closure", not "bound to nextcolor", since the word "bound" is usually used to talk about variable names ("identifiers") and their values. Similarly, in the next sentence, I should have pointed out that when you call the returned value, you're not just calling nextcolor but the closure over nextcolor, which includes the bindings for cs and i.