vertical quarry

while true do

    redstone.setAnalogOutput("left", 15)

    os.pullEvent("redstone")
    if rs.getInput("top") then
        redstone.setAnalogOutput("left", 0)
        sleep(1)
        redstone.setAnalogOutput("back", 15)
    end

    os.pullEvent("redstone")
    if rs.getInput("top") then
        redstone.setAnalogOutput("back", 0)
        sleep(1)
        redstone.setAnalogOutput("right", 15)
    end

    os.pullEvent("redstone")
    if rs.getInput("top") then
        redstone.setAnalogOutput("right", 0)
        sleep(1)
    end

end