This isn't a common usage term. The 'iterator' is the person making a statement of iteration, requiring repetition of an action. This is an uncommon term in modern usage, and has limited functions unless it's necessary to refer to someone making a statement of this type. Although it's an anachronism, it also relates to other terms like 'iterative', referring to the verb. The main current usage is literary, although it may also be used in an academic context.