code: def _modify_tag(self, name, description, servers, new_name):
          
          body = {'tag': Tag(new_name, description, servers).to_dict()}
          res = self.request('PUT', '/tag/' + name, body)
          return res['tag']
docs: PUT /tag/name. Returns a dict that can be used to create a Tag object.
  
          Private method used by the Tag class and TagManager.modify_tag.