ClearTree v0.3

function forward(count)
  for i = 1, count do
    turtle.forward()
  end
end

function turnLeft(count)
  for i = 1, count do
    turtle.turnLeft()
  end
end

function turnRight(count)
  for i = 1, count do
    turtle.turnRight()
  end
end

function cl()
  for i = 1, 7 do
    turtle.digDown()
    turtle.down()
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.dig()
    turtle.turnLeft()
    turtle.turnLeft()
  end
  for i = 1, 7 do
    turtle.up()
  end
end

function one()
  for j = 1, 4 do
    cl()
    turtle.turnLeft()
    turtle.forward()
    turtle.turnRight()
    turtle.forward()
    turtle.turnRight()
  end
end

function row()
  for i = 1, 4 do
    one()
    turnRight(1)
    forward(3)
    turnLeft(1)
  end
  one()
end

function main()
  for i = 1, 9 do
    turtle.digUp()
    turtle.up()
  end
  for i = 1, 4 do
    row()
    turnLeft(1)
    forward(13)
    turnRight(1)
    forward(3)
    turnRight(1)
    forward(1)
    turnLeft(1)
  end
  row()
  turnLeft(1)
  forward(13)
  turnLeft(1)
  forward(12)
  turnLeft(1)
  forward(1)
  turnLeft(1)
  for i = 1, 9 do
    turtle.down()
  end
end

main()