middle

right = function()
redstone.setOutput("right", false)
while not redstone.getInput("right") do
  os.queueEvent("randomEvent")
  os.pullEvent()
end
return "left"
end


left = function()
redstone.setOutput("left", false)
while not redstone.getInput("left") do
  os.queueEvent("randomEvent")
  os.pullEvent()
end
return "right"
end


while true do

side = parallel.waitForAny(left, right)

if side == 1 then
  redstone.setOutput("right", true)
  os.sleep(3)
  redstone.setOutput("right", false)
end
if side == 2 then
  redstone.setOutput("left", true)
  os.sleep(3)
  redstone.setOutput("left", false)
end

end