Help with strings?

im trying to make a script that adds a dot every second on a string value. but im assuming this is impossible to do with roblox's inability to have the append feature?

local str = "";
while wait(1) do -- Every 1 second, do
	srt = str .. "."; -- Concatenate a dot to the string
end

Also (addition from ninjo) if you are talking about the StringValue object, you can just concatenate the dot to it's value. So str.Value = str.Value .. ".";