Function frappe::lift::lift4

pub fn lift4<T, F, S1, S2, S3, S4>(
    f: F, 
    s1: Signal<S1>, 
    s2: Signal<S2>, 
    s3: Signal<S3>, 
    s4: Signal<S4>
) -> Signal<T> where
    F: Fn(MaybeOwned<S1>, MaybeOwned<S2>, MaybeOwned<S3>, MaybeOwned<S4>) -> T + 'static,
    T: 'static,
    S1: 'static,
    S2: 'static,
    S3: 'static,
    S4: 'static, 

Lifts a function into a signal.