local black = false

function ending()
  turtle.turnRight()
  turtle.forward()
  turtle.turnRight()
end

for i = 0, 6 do
  if black then
    turtle.select(1)
  else
    turtle.select(2)
  end

  for i = 0, 2 do
    turtle.placeDown()
    turtle.forward()
  end

  black = not black
end