Add a 3 second delay to a script

This piece of code runs every time my customer uses the command @refresh. I would like to add a 3 second cool down to the @refresh command. This means that the first time they do @refresh it will work fine, however if they use @refresh again 1 second after it will say "This command has a 3 second cool down". Here is a look at the code: /*========================================== * @refresh (like @jumpto <<yourself>>) *------------------------------------------*/ ACMD_FUNC(refresh) { nullpo_retr(-1, sd); clif_refresh(sd); return 0; }