code: func GetReqID(ctx context.Context) string {
  	if ctx == nil {
  		return ""
  	}
  	if reqID, ok := ctx.Value(RequestIDKey).(string); ok {
  		return reqID
  	}
  	return ""
  }
docs: // GetReqID returns a request ID from the given context if one is present.
  // Returns the empty string if a request ID cannot be found.