Function plan_overflow 

pub fn plan_overflow(
    width: f64,
    widths: impl IntoIterator<Item = f64>,
    gap: f64,
    door: f64,
) -> usize

How many of a row’s items, widths wide in the row’s order with gap between them, stand in width beside a door door wide ([give_way]); the rest are behind the door, in the same order. A row does not reorder its commands to fit more of them, because the order is what makes them findable.