I want to execute a command if user has a permission.

Where do I place the `permission check` in my plugin command code?

```
public class wingsOff implements CommandExecutor {

    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {

        if(label.equalsIgnoreCase("disableflight")) {
            if (!(sender instanceof Player)) {
                sender.sendMessage("Sorry! Only players can do this.");
                return false;
            }

            Player player = (Player) sender;
            player.sendMessage(ChatColor.GOLD + "Flight mode disabled!");
            player.setAllowFlight(false);

            return true;       
        }

        return false;
    }   
}

```