if gz:
                f = gzip.open(file+".gz", "w")
                if os.path.exists(file):
                    os.unlink(file)
            else:
                f = open(file, "w")
            # encode
            json.dump(data, f, indent=(4 if nice else None))
            data = json.dumps(data, indent=(4 if nice else None))
            f.write(data.encode("utf-8"))
            f.close()


        # retrieve data from config file            
        def load(self, name):
            name = name + ".json"
            file = self.dir + "/" + name