code: func (server *Server) SendChordWithContext(ctx context.Context, chord *tasks.Chord, sendConcurrency int) (*result.ChordAsyncResult, error) {
  	span, _ := opentracing.StartSpanFromContext(ctx, "SendChord", tracing.ProducerOption(), tracing.MachineryTag, tracing.WorkflowChordTag)
  	defer span.Finish()
  
  	tracing.AnnotateSpanWithChordInfo(span, chord, sendConcurrency)
  
  	_, err := server.SendGroupWithContext(ctx, chord.Group, sendConcurrency)
  	if err != nil {
  		return nil, err
  	}
  
  	return result.NewChordAsyncResult(
  		chord.Group.Tasks,
  		chord.Callback,
  		server.backend,
  	), nil
  }
docs: // SendChordWithContext will inject the trace context in all the signature headers before publishing it