Function add 

pub fn add<D, S, Op>(
    dest: &mut StridedViewMut<'_, D>,
    src: &StridedView<'_, S, Op>,
) -> Result<(), StridedError>
where
    D: Copy + Add<S, Output = D> + MaybeSendSync,
    S: Copy + MaybeSendSync,
    Op: ElementOp<S>,

Element-wise addition: dest[i] += src[i].

Source may have a different element type from destination.