2x2tree

local height = 1

function fuel()
    if turtle.getFuelLevel() == 0 then
        turtle.refuel(1)
    end
end

turtle.dig()
fuel()
turtle.forward()
while turtle.detectUp() do
    turtle.dig()
    turtle.digUp()
    fuel()
    turtle.up()
    height = height + 1
end
turtle.turnRight()
turtle.dig()
fuel()
turtle.forward()
turtle.turnLeft()
while height > 1 do
    turtle.dig()
    turtle.digDown()
    fuel()
    turtle.down()
    height = height - 1
end
turtle.dig()
fuel()
turtle.back()
turtle.turnLeft()
fuel()
turtle.forward()
turtle.turnRight()
for slot=1,16 do
    turtle.select(slot)
    turtle.dropDown()
end