Showing spectators

I need some help with creating a script that shows people spectating you in a little box or whatever (like Ahack). I know I'm going to need to use GetObserverTarget but I need a little help doing it.
Please don't post irrelevant shit, thank you.

for k, v in pairs (player.GetAll()) do
if(v:GetObserverTarget() == LocalPlayer()) then
printf("noob %s is watching you",v:Nick())
end
end

if getobservertarget actually exists

I was studying the 'show spectators' code from SethHack, Hera & AHack and tried to create my own script:
http://pastebin.com/u4Gw9ZuU

I get this shit when running it:

[ERROR] lua/test.lua:4: ')' expected near 'v'
1. unknown - lua/test.lua:0