night

function refuel()

local f = 0

f = turtle.getFuelLevel()

if f<20 do
  turtle.select(3)
  turtle.suckDown()
  turtle.refuel(3)
end

while true do
  refuel()
  turtle.select(1)
  turtle.digUP()
  turtle.up(2)
  turtle.placeDown()
  turtle.up(24)
  turtle.select(2)
  turtle.placeDown()
end