old_contents: class Py3status:
      """
      Empty and basic py3status class
      """
      def empty(self, json, i3status_config):
          """
          This method will return an empty text message, so it will NOT be displayed.
          If you want something displayed you should write something in the 'full_text' key of your response.
          See the i3bar protocol spec for more information:
              http://i3wm.org/docs/i3bar-protocol.html
          """
          response = {'full_text' : '', 'name' : 'empty'}
          return (0, response)
  
new_contents: class Py3status:
      """
      Empty and basic py3status class.
  
      NOTE: py3status will NOT execute :
          - methods starting with '_'
          - methods decorated by @property and @staticmethod
      """
      def empty(self, json, i3status_config):
          """
          This method will return an empty text message, so it will NOT be displayed.
          If you want something displayed you should write something in the 'full_text' key of your response.
          See the i3bar protocol spec for more information:
              http://i3wm.org/docs/i3bar-protocol.html
          """
          response = {'full_text' : '', 'name' : 'empty'}
          return (0, response)
  
subject: add information about method execution in the empty_class example