code: def fetch_official_missions(data_dir, start_date, end_date):
      
      official_missions = OfficialMissionsDataset()
      df = official_missions.fetch(start_date, end_date)
      save_to_csv(df, data_dir, "official-missions")
  
      return df
docs: :param data_dir: (str) directory in which the output file will be saved
      :param start_date: (datetime) first date of the range to be scraped
      :param end_date: (datetime) last date of the range to be scraped