Add blacklist packages if not exist

def add(self, pkgs):
        """Add blacklist packages if not exist
        """
        blacklist = self.get_black()
        pkgs = set(pkgs)
        print("\nAdd packages in the blacklist:\n")
        with open(self.blackfile, "a") as black_conf:
            for pkg in pkgs:
                if pkg not in blacklist:
                    print("{0}{1}{2}".format(self.meta.color["GREEN"], pkg,
                                             self.meta.color["ENDC"]))
                    black_conf.write(pkg + "\n")
                    self.quit = True
            black_conf.close()
        if self.quit:
            print("")