[rdtsc]

I forgot what the word meant so here is the definition for anyone else:

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A custom, principle, or belief distinguishing a particular class or group of people, especially a long-standing one regarded as outmoded or no longer important.

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Besides the mentioned Github and open source project participation other shibboleth I use is some experience or knowledge of functional languages -- Scala, Haskell, Lisp, Erlang, F# and such.

I don't use them as hard guidelines but these just proved to be good heuristics in the past. Chances are high if someone is good at Haskell they will be good at many hard problems we throw at them.