code: func InstrumentHandlerFunc(handlerName string, handlerFunc func(http.ResponseWriter, *http.Request)) http.HandlerFunc {
  	return InstrumentHandlerFuncWithOpts(
  		SummaryOpts{
  			Subsystem:   "http",
  			ConstLabels: Labels{"handler": handlerName},
  			Objectives:  map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
  		},
  		handlerFunc,
  	)
  }
docs: // InstrumentHandlerFunc wraps the given function for instrumentation. It
  // otherwise works in the same way as InstrumentHandler (and shares the same
  // issues).
  //
  // Deprecated: InstrumentHandlerFunc is deprecated for the same reasons as
  // InstrumentHandler is. Use the tooling provided in package promhttp instead.