Single stack cobble generator, v1

    start=os.clock()

    t=turtle

    -- get the buckets from the chest:
    t.select(1)
    t.suck()
    t.refuel()
    t.suck()
    t.suck()

    -- build the farm:
    t.turnLeft()
    t.digDown()
    t.forward()
    t.digDown()
    t.turnLeft()
    t.down()
    t.dig()
    t.forward()
    t.digDown()
    t.turnLeft()
    t.dig()
    t.down()
    t.dig()
    t.turnRight()
    t.dig()
    t.select(1)
    t.place()
    t.turnLeft()
    t.forward()
    t.turnRight()
    t.dig()
    t.drop()
    t.up()
    t.turnRight()
    t.turnRight()
    t.select(2)
    t.place()
    t.dropDown()
    t.turnLeft()

    t.select(1)
    for i=1,32 do
      sleep(1)
      t.forward()
      t.digDown()
      sleep(1)
      t.back()
      t.digDown()
    end

    -- deposit the cobble into the chest:
    t.up()
    t.turnRight()
    t.forward()
    t.drop(64)

    elapsed = os.clock()-start
    print("Finished in "..elapsed.." seconds.")