Library code: Woodcutting bot

-- Color: Brown
step = 0
turtle.dig()
turtle.forward()
while true do
  if turtle.compareUp() then
    turtle.digUp()
    turtle.up()
    step = step + 1
  else
    while step > 0 do
      turtle.down()
      step = step - 1
    end
    turtle.backwards()
    for i = 0, 16 do
      turtle.select(i)
      turtle.dropUp(64)
    end
    turtle.select(1)
    break
end