code: func RegisterXRayInterceptor(handler *sparta.LambdaEventInterceptors,
  	mode XRayInterceptorMode) *sparta.LambdaEventInterceptors {
  	interceptor := &xrayInterceptor{
  		mode: mode,
  	}
  	if handler == nil {
  		handler = &sparta.LambdaEventInterceptors{}
  	}
  	return handler.Register(interceptor)
  }
docs: // RegisterXRayInterceptor handles pushing the tracing information into XRay