go.opencensus.io/plugin/ochttp/propagation/b3.HTTPFormat.SpanContextFromRequest (method)

one use

	go.opencensus.io/plugin/ochttp/propagation/b3 (current package)
		b3.go#L48: func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) {