Serum Filling Automation

function serumfiller()
  if rs.getInput("bottom") then
    rs.setOutput("back", true)
    sleep(0.05)
    rs.setOutput("back", false)
  end
  sleep(0.3)
  if rs.getInput("top") then
    rs.setOutput("right", true)
    sleep(0.05)
    rs.setOutput("right", false)
  end
end

local on = true
local interval = 3

local timer = os.startTimer(0)
while on do
   local event, p1, p2, p3 = os.pullEvent()
   if event == "timer" then
           --Update program
           timer = os.startTimer(interval)
           serumfiller()
   elseif event == "key" then
           if p1 == 45 then --x
                   on = false
           end
   end
end