code: def set_title(self, index, title):
          
          # JSON dictionaries have string keys, so we convert index to a string
          index = unicode_type(int(index))
          self._titles[index] = title
          self.send_state('_titles')
docs: Sets the title of a container page.
  
          Parameters
          ----------
          index : int
              Index of the container page
          title : unicode
              New title