option.rs

impl<T: Copy Add<T,T>> Option<T> : Add<Option<T>, Option<T>> {
    #[inline(always)]
    pure fn add(other: &Option<T>) -> Option<T> {
        match (self, *other) {
            (None, None) => None,
            (_, None) => self,
            (None, _) => *other,
            (Some(ref v1), Some(ref v2)) => Some(*v1 + *v2)
        }
    }
}