Python was created in 1991; I imagine the "yield" keyword appeared either right then or not much later!

Also, the refinement at the end of the article: "We arrange an extra function parameter, which is a pointer to a context structure; we declare all our local state, and our coroutine state variable, as elements of that structure." sounds like implementing a closure to me. You make the callee a lambda which would use an outside var/context/state to determine what to do or with what value. Am I understanding this correctly?