docs: def pretty(self, indent=0, indent_str='  '):
          """
          Pretty-print a tag in the same general style as Markus's example
          output.
          """
          return '{0}{1}({2!r}): {3!r}'.format(
              indent_str * indent,
              self.__class__.__name__,
              self.name,
              self.value
          )