1 and 20 chance of you getting a weapon?

Can someone give me a piece of code where you have a 1 and 20 chance of getting the weapon weapon_stunstick after you press a derma button.

[lua]if math.random(1,20)==1 then
ply:Give(“weapon_stunstick”)
end[/lua]
this will only work if ply is defined

Thanks it worked perfectly!