code: def _extract_annotations_from_span(span):
      
      if span.time_events is None:
          return []
  
      annotations = []
      for time_event in span.time_events:
          annotation = time_event.annotation
          if not annotation:
              continue
  
          event_timestamp_mus = timestamp_to_microseconds(time_event.timestamp)
          annotations.append({'timestamp': int(round(event_timestamp_mus)),
                              'value': annotation.description})
  
      return annotations
docs: Extract and convert time event annotations to zipkin annotations