code: def add_annotation(self, description, **attrs):
          
          at = attributes.Attributes(attrs)
          self.add_time_event(time_event_module.TimeEvent(datetime.utcnow(),
                              time_event_module.Annotation(description, at)))
docs: Add an annotation to span.
  
          :type description: str
          :param description: A user-supplied message describing the event.
                          The maximum length for the description is 256 bytes.
  
          :type attrs: kwargs
          :param attrs: keyworded arguments e.g. failed=True, name='Caching'