function wait(condition, compare, cb)
    compare = compare == nill and true or compare

    while (condition ~= compare) do
        if (cb) then
            cb()
        end
        os.sleep(0.1)
    end

    return true
end

function fuel() {
    local old = turtle.getSelectedSlot()

    while (turtle.getFuelLevel() < 10) do
        turtle.select(16)
        turtle.refuel()
    end

    turtle.select(old)
}

function forward(steps) {
    fuel()
    wait(turtle.forward)

    return true
}

function up(steps) {
    fuel()
    wait(turtle.up)

    return true
}

turtle.select(1)
wait(turtle.compare)
turtle.dig()
forward()

function a()
    turtle.digUp()
    up()
end

wait(turtle.detectUp, false, a)

wait(turtle.down, false)

turtle.turnRight()
turtle.turnRight()
forward()
turtle.turnRight()
turtle.turnRight()