Is it always safe to “re-use” an iterator/generator?

[lmtzx9h4qqnt]

A relevant previous discussion:

Iterators.Stateful is not an iterator?

I’m trying to understand iterators better because I’m trying to decide whether I should, for my specific application, define iterate for my type or define a constructor of Iterators.Stateful for my type. And I seem to have reached the conclusion that Iterators.Stateful aren’t iterators? The interfaces page [1] says that to implement the interator interface, two methods are required: iterate(iter) Returns either a tuple of the first item and initial state or nothing if empty iterate(iter, …