code: def get_timezone_name(self):
          
          tz_name = self.conn.execute('SELECT timezone FROM agencies LIMIT 1').fetchone()
          if tz_name is None:
              raise ValueError("This database does not have a timezone defined.")
          return tz_name[0]
docs: Get name of the GTFS timezone
  
          Returns
          -------
          timezone_name : str
              name of the time zone, e.g. "Europe/Helsinki"