slot =1
function pos ()
turtle.digDown()
turtle.placeDown()
turtle.forward()
turtle.digDown()
turtle.placeDown()
turtle.forward()
end

function av ()
turtle.forward()
turtle.forward()
turtle.forward()
turtle.forward()
turtle.forward()

end

function change ()
slot=slot+1
if (slot==17) then
slot=1
end
turtle.select(slot)

end

while true do
av()
change()
pos()
end