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 while