function fuelCheck()
    if turtle.getFuelLevel() < 10
    then
        turtle.refuel()
    end
end

for i = 1, 25, 1 do
    fuelCheck()
    if turtle.detectDown()
    then
        turtle.digDown()
        turtle.suckDown()
        turtle.down()
    end
    if turtle.detect()
    then
        turtle.dig()
        turtle.suck()
        turtle.forward()
    end
end