/// Notifable is a type that can be notified when the `AsyncIterator`
/// is ready.
/// [`CanNotifyOfSelf`] defines a type whose underlying behave can deliver
/// notification of it's self to others.
///
/// It exposes a [`CanNotify::register`] method that allows you
/// register for notification with it where it notifies you of it's
/// state when received.
/// `CanNotifyOfSelf` defines a type whose underlying behave can deliver
/// notification of it's self to others.
///
/// It exposes a [`CanNotify::register`] method that allows you
/// register for notification with it where it notifies you of it's
/// state when received.