docs: def list_tags(self, pattern: str = None) -> typing.List[str]:
          """
          Returns list of tags, optionally matching "pattern"
  
          :param pattern: optional pattern to filter results
          :type pattern: str
          :return: existing tags
          :rtype: list of str
          """
          tags: typing.List[str] = [str(tag) for tag in self.repo.tags]
          if not pattern:
              LOGGER.debug('tags found in repo: %s', tags)
              return tags
  
          LOGGER.debug('filtering tags with pattern: %s', pattern)
          filtered_tags: typing.List[str] = [tag for tag in tags if pattern in tag]
          LOGGER.debug('filtered tags: %s', filtered_tags)
          return filtered_tags