Turtle: Mine

function next()
    turtle.dig()
    turtle.forward()
    turtle.dig()
    turtle.forward()
    turtle.turnRight()
    turtle.dig()
    turtle.forward()
    turtle.turnLeft()
end
b = true
function fuel()
  if turtle.getFuelLevel() <= 10 then
    turtle.select(16)
    turtle.refuel(tonumber(1))
    turtle.select(1)
  end
end
dep = 0

function bed()
  turtle.digDown()
  if turtle.detectDown() then
  b = false
  end
end

function sides()
  for i = 1,4 do
    turtle.dig()
    turtle.turnRight()
  end
end
function down()
  fuel()
  if b then
    turtle.down()
    sides()
    dep = dep + 1
  end
end

function up()
  for dep = dep , 1 , -1 do

    fuel()
    sides()
    turtle.digUp()
    sleep(.5)
    while turtle.detectUp() do
      turtle.digUp()
      sleep(.5)
    end
    if dep == 1 then
      for i = 1,4 do
      turtle.place()
      turtle.turnRight()
      end
    end
    turtle.up()
  end
end

while b do
  bed()
  down()
end
for u = 1,6 do
  turtle.up()
  dep = dep - 1
end
next()
b = true
while b do
  bed()
  down()
end
up()
turtle.placeDown()