Room Clearing/Digging Turtle

print("Loading Robust Turtle API...")
local load = os.loadAPI("t")
if load then
  print("Robust Turtle API loaded.")
else
 print("Robust Turtle API not found in the root directory with filename t")
 print("Attempting to download as t from pastebin...")
 os.sleep(1)
 local response = http.get("http://pastebin.com/raw.php?i= e0UksEtT")
 if response then
    print("Great Success.")
    local data = response.readAll()
    response.close()
    local file = fs.open("t", "w")
    file.write(data)
    file.close()
    print("Downloaded as t")
    load = os.loadAPI("t")
    if load then
     print("Robust Turtle API installed & loaded.")
    end
 else
    print( "Download Failed. Please Install Manually." )
    return
 end
end


--room clearer

function layer(l,w)
    local alternate = "right"
    for i =1, w do
        t.forward(l)
        if alternate == "right" and i~=w then
            t.right()
            t.forward()
            t.right()
            alternate = "left"
        elseif alternate == "left" and i~=w then
            t.left()
            t.forward()
            t.left()
            alternate = "right"
        elseif alternate == "left" and i==w then
            t.right()
            t.forward(w-1)
            t.right()
        elseif alternate == "right" and i==w then
            t.strafeLeft(w-1)
            t.back(l)
        end
    end
end

term.clear()
term.setCursorPos(1,1)
print("Room Clearer Turtle. ")
print("length?")
local length = (t.readNum()-1)
print("width?")
local width = t.readNum()
print("height of room?")
local height = t.readNum()


t.forward()
t.strafeLeft(width/2)
for i=1, height do
  layer(length,width)
  --does not move up after digging last layer
  if i ~= height then
    t.up()
  end
end
t.sDown(height-1)
t.sStrafeRight(width/2)