The router function uses the HeaderExtractor to extract trace context from incoming requests’ headers, setting it as the parent context for the current span.
The first thing is what it tells us about who J. D. Vance is. The bank teller story—how ATMs were predicted to increase bank teller unemployment, but in fact did not—isn’t a story you’ll hear from politicians; in fact, for a long time, Barack Obama would claim, incorrectly, that ATMs had decreased the number of bank tellers, in order to suggest that the elevated unemployment rate during his presidency was due to productivity gains from technology. I’ve never heard a politician cite the bank teller story before: but I have seen the bank teller story cited in a lot of blogs. I’ve seen it cited, for example, by Scott Alexander and Matt Yglesias and Freddie deBoer; and I’ve heard it, upstream of the humble bloggers, from such fine economists as Daron Acemoglu and David Autor. The story of how ATMs didn’t automate bank tellers is, indeed, something of a minor parable of the economics profession. You can see it encapsulated in this wonderful graph from the economist James Bessen:
，这一点在搜狗输入法中也有详细论述
Последние новости，这一点在手游中也有详细论述
南方周末：你最期待的一项政策是什么？，这一点在超级权重中也有详细论述
void foo(int...); // without comma (C++-only)