pub fn dyn_stack<IF, I, T, KF, K, VF, V>( each_fn: IF, key_fn: KF, view_fn: VF ) -> DynStack<V, T>where IF: Fn() -> I + 'static, I: IntoIterator<Item = T>, KF: Fn(&T) -> K + 'static, K: Eq + Hash + 'static, VF: Fn(T) -> V + 'static, V: View + 'static, T: 'static,