pub fn simple_linear_regression_with_slope<V, F, A>(
    slope: V,
    values: A
) -> Anim<Line<V>>where
    V: 'static + FloatCore + Copy,
    F: Fun<T = usize, V = (V, V)>,
    A: Into<AnimWithDur<F>>,
    usize: AsPrimitive<V>,