multi screens

[basconje]

Hi
I am trying use this nice framework , but I am struggling in problem how to manage state in multi screens application , can you provide a simple example of application with some screens , and in example with signIn :

static var feedback: Feedback<State, Event> {
return Feedback.combine(
whenChangingUserName(api: GithubAPI()),
whenSubmitting(api: GithubAPI())
)
}
why need it ?
Thanks in advance.