docs: def create_tag(self, tag_name):
          """
          Create a new tag based on the working tree's revision.
  
          :param tag_name: The name of the tag to create (a string).
          """
          # Make sure the local repository exists and supports a working tree.
          self.create()
          self.ensure_working_tree()
          # Create the new tag in the local repository.
          logger.info("Creating tag '%s' in %s ..", tag_name, format_path(self.local))
          self.context.execute(*self.get_create_tag_command(tag_name))