Function daemon 

pub fn daemon<State, Message, Theme, Renderer>(
    boot: impl BootFn<State, Message>,
    update: impl UpdateFn<State, Message>,
    view: impl for<'a> ViewFn<'a, State, Message, Theme, Renderer>,
) -> Daemon<impl Program<State = State, Message = Message, Theme = Theme>>
where
    State: 'static,
    Message: Send + 'static,
    Theme: Base,
    Renderer: Renderer,

Creates an iced Daemon given its boot, update, and view logic.

A Daemon will not open a window by default, but will run silently instead until a Task from window::open is returned by its update logic.

Furthermore, a Daemon will not stop running when all its windows are closed. In order to completely terminate a Daemon, its process must be interrupted or its update logic must produce a Task from exit.