docs: def get_version(self):
          """
          Return the stringified version passed to the templatetag.
          """
          if not self.node.version:
              return None
          try:
              version = smart_str('%s' % self.node.version.resolve(self.context))
          except template.VariableDoesNotExist:
              raise template.TemplateSyntaxError('"%s" tag got an unknown variable: %r' %
                                                 (self.node.nodename, self.node.version.var))
  
          return '%s' % version