Redstone Level Emitter

--if #args == 0 then   --If no arguments, give a text prompt instead
local lvl = 0
function getnumber(num)
    lvl = tonumber(num)
    assert(lvl ~= nil, "not a number")
    assert(lvl <= 30, "number too large")
    return lvl
end

while true do
    print()
    print('What redstone level [0-30]?')
    write('Enter a number (negative exits): ')
    num = read()
    status, lvl = pcall(getnumber, num)
    --print(status, lvl)
    if status then
        if lvl < 0 then
            rs.setAnalogOutput('right', 0)
            rs.setAnalogOutput('top', 0)
            break
        else
            lvls = math.floor(lvl / 16)
            lvlr = lvl % 16
            --print(tostring(lvls), tostring(lvlr))
            if lvls > 0 then
                level_right = lvlr+1
                level_top = 15
            else
                level_right = lvlr
                level_top = 0
            end
            print("Right:", level_right)
            print("Top:", level_top)
            rs.setAnalogOutput('right', level_right)
            rs.setAnalogOutput('top', level_top)
        end
    else
        print(lvl)
    end
end