code: func (server *Server) SendChainWithContext(ctx context.Context, chain *tasks.Chain) (*result.ChainAsyncResult, error) {
  	span, _ := opentracing.StartSpanFromContext(ctx, "SendChain", tracing.ProducerOption(), tracing.MachineryTag, tracing.WorkflowChainTag)
  	defer span.Finish()
  
  	tracing.AnnotateSpanWithChainInfo(span, chain)
  
  	return server.SendChain(chain)
  }
docs: // SendChainWithContext will inject the trace context in all the signature headers before publishing it