mine

function detectGravelFront()
  while turtle.detect()==true do
    turtle.dig()
  end
end

function digging()
  turtle.dig()
  detectGravelFront()
  turtle.forward()
  turtle.digUp()
  turtle.digDown()
end

function turnPravo()
  turtle.turnRight()
  digging()
  turtle.turnRight()
end

function turnLevo()
  turtle.turnLeft()
  digging()
  turtle.turnLeft()
end

function turtleVniz()
  turtle.down()
  turtle.digDown()
  turtle.down()
  turtle.digDown()
  turtle.down()
end

write("Write your Y level: ")
height=read()
height=height+0
oldHeight=height
height=height-6

h=1

while height>h do
  digging()
  for i=1,4 do
    for i=1,7 do
      digging()
    end
    turnPravo()
    for i=1,7 do
      digging()
    end
    turnLevo()
  end
  turtle.turnLeft()
  turtleVniz()
  h=h+3
end