pub fn linear<T, T1, F>(
    handle: Handle<T1>,
    lens: F,
    from: T,
    to: T,
    time: f32
) -> LinearTweenFuture<T> 
where T: Copy + Add<Output = T> + Sub<Output = T> + Mul<f32, Output = T>, T1: Node, F: for<'r> FnMut(&'r mut T1) -> &'r mut T,