use std::usize;
pub type SizeHint = (usize, Option<usize>);
#[inline]
pub fn add(a: SizeHint, b: SizeHint) -> SizeHint {
let min = a.0.saturating_add(b.0);
let max = match (a.1, b.1) {
(Some(x), Some(y)) => x.checked_add(y),
_ => None,
};
(min, max)
}