procedure main(A)
    showTree("", " -", [1, [2,[3],[4,[5],[6]],[7,[11]]], [8,[9,[10]]] ])
    write()
    showTree("", " -", [1, [2,[3,[4]]], [5,[6],[7,[8],[9]],[10]] ])
end

procedure showTree(prefix, lastc, A)
    write(prefix, lastc, "--", A[1])
    if *A > 1 then {
        prefix ||:= if prefix[-1] == "|" then "   " else "    "
        every showTree(prefix||"|", "-", !A[2:2 < *A])
        showTree(prefix, "`-", A[*A])
        }
end