code: def format(self):
          
          subtag = self.data['subtag']
          if self.data['type'] == 'region':
              return subtag.upper()
          if self.data['type'] == 'script':
              return subtag.capitalize()
          return subtag
docs: Get the subtag code conventional format according to RFC 5646 section 2.1.1.
  
          :return: string -- subtag code conventional format.