code: def create_default_config(self):
          
          filename = self.config_file.as_posix()
          logger.info("Creating default config file: %s", filename)
          config_dir = self.config_file.parent
          if not config_dir.exists():
              config_dir.mkdir(parents=True)
          if self.config_file.is_file():
              backup = filename + ".old"
              logger.info("Saving config file backup at: %s", backup)
              shutil.copy(filename, backup)
          with open(self.config_file, mode="w") as f:
              config_string = CONFIG_TEMPLATE.format(
                  data_dir=self.default_config["data dir"],
                  linewrap=self.default_config["linewrap"],
                  colors=self.default_config["colors"],
                  browser=self.default_config["web browser"],
              )
              f.write(config_string)
          return filename
docs: Write default config file to disk.
  
          Backs up existing configuration file.
  
          Returns
          -------
          filename : string
              Path to config file.