"Three programmers come to a one-way street. The academic looks to the right, doesn't see any oncoming cars, and crosses. The corporate programmer looks to the left, then looks to the right, and then crosses. The distributed systems engineer looks to the left, then looks to the right, then looks up to make sure there aren't any planes falling out of the sky…"
"... the hacker looks down to check for landmines and footguns, and then runs to catch up with the rest, grumbling something about computer scientists and off-by-one errors."
The distributed systems engineer definitely uses a mirror to watch both directions at the same time while crossing the street. They've been caught by Time of Check - Time of Use errors before.
