code: func FlushLightStepTracer(tracer opentracing.Tracer) error {
  	switch lsTracer := tracer.(type) {
  	case Tracer:
  		lsTracer.Flush(context.Background())
  		return nil
  	case *tracerv0_14:
  		return FlushLightStepTracer(lsTracer.Tracer)
  	default:
  		return newEventUnsupportedTracer(tracer)
  	}
  }
docs: // FlushLightStepTracer flushes the tracer
  // DEPRECATED: use Flush instead.