code: def create_new_locale(
          self,
          template_id,
          locale,
          version_name,
          subject,
          text='',
          html='',
          timeout=None
      ):
          
          payload = {
              'locale': locale,
              'name': version_name,
              'subject': subject
          }
  
          if html:
              payload['html'] = html
          if text:
              payload['text'] = text
  
          return self._api_request(
              self.TEMPLATES_LOCALES_ENDPOINT % template_id,
              self.HTTP_POST,
              payload=payload,
              timeout=timeout
          )
docs: API call to create a new locale and version of a template