Function component 

pub fn component<'a, C, Message, Theme, Renderer>(
    component: C,
) -> impl Widget<Message, Theme, Renderer> + 'a
where
    C: Component<'a, Message, Theme, Renderer> + 'a,
    <C as Component<'a, Message, Theme, Renderer>>::State: 'static,
    Message: 'a,
    Theme: 'a,
    Renderer: Renderer + 'a,

Turns an implementor of Component into an Element that can be embedded in any application.