pub trait FuFn8<T0, T1, T2, T3, T4, T5, T6, T7>: FuFnMut8<T0, T1, T2, T3, T4, T5, T6, T7, Output = Self::Future> + Fn(T0, T1, T2, T3, T4, T5, T6, T7) { }