(i.10) showtree _,}.p:inv i.10
                 ┌─ 6
     ┌─ 1 ─── 3 ─┴─ 7
     │           ┌─ 8
─ 0 ─┤     ┌─ 4 ─┴─ 9
     └─ 2 ─┴─ 5