timer

while true do
    if rs.getInput("back") == false then
        term.clear()
        term.setCursorPos(1, 1)
        for i=1,5 do
            term.clearLine()
            term.write("pulse "..i.."/5")
            rs.setOutput("left", true)
            sleep(1)
            rs.setOutput("left", false)
            sleep(1)
        end
    else
        term.clear()
        term.setCursorPos(1, 1)
        term.write("waiting...")
        sleep(5)
    end
end