code: func (jst *Tracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
  	jst.ctx["output"] = output
  	jst.ctx["gasUsed"] = gasUsed
  	jst.ctx["time"] = t.String()
  
  	if err != nil {
  		jst.ctx["error"] = err.Error()
  	}
  	return nil
  }
docs: // CaptureEnd is called after the call finishes to finalize the tracing.