Function render_owing 

pub fn render_owing(
    selected: &[&Challenge],
    topics: &[String],
    owed: usize,
) -> Option<(String, usize)>

render_early whose first owed lessons are shown whatever the budget and count nothing toward it: a free delivery’s hand-overs in place of questions the fixed rule asks (hook.rs INSTEAD, the question-count test’s, and INSTEAD_NEXT, the evidence rule’s), which the asks they replace would have carried without a bound. The rest fit EARLY_CHARS as they would without them.