How to use the nikola.utils.LOGGER.warning function in Nikola

LOGGER.info("processing " + fname)
            try:
                # data = load_json(fname)
                data = {}
                data["path"] = fname
                data["path_image"] = fname[:-3] + ".png"
                data["name"] = os.path.basename(os.path.dirname(fname))
                data["url"] = "https://github.com/undertherain/pycontextfree/blob/master/examples/" + data["name"] + "/" + os.path.basename(fname)
                data["id"] = cnt
                name_image = os.path.basename(fname)[:-3] + ".png"

                data["image"] = "/gallery/" + name_image
                cnt += 1
                self.rows.append(data)
            except Exception as e:
                LOGGER.warning("error processing " + fname + str(e))