clear
s = "Hello World! "
toggle = true
while true
	text.row = 12
	text.column = 15
	print " " + s + " "
	wait 0.1
	if key.available then
		toggle = not toggle
		key.clear
		yield
	end if
	if toggle then
		s = s[-1] + s[:-1]
	else
		s = s[1:] + s[0]
	end if
end while