code: def to_JSON(self):
          
          return json.dumps({'id': self.id,
                             'external_id': self.external_id,
                             'name': self.name,
                             'created_at': timeformatutils.to_ISO8601(self.created_at),
                             'updated_at': timeformatutils.to_ISO8601(self.updated_at),
                             'lat': self.lat,
                             'lon': self.lon,
                             'alt': self.alt if self.alt is not None else 'None',
                             'rank': self.rank})
docs: Dumps object fields into a JSON formatted string
  
          :returns: the JSON string