I was working with a research team at UCLA and we used Wolfram Mathematica to process our results. In Mathematica, pretty much any object can be a variable nam

I was working with a research team at UCLA and we used Wolfram Mathematica to process our results. In Mathematica, pretty much any object can be a variable name. You can drag a JPEG of Kim Jong-un into Mathematica and integrate an expression with respect to Kim Jong-un. We'd sometimes get a kick out of that. Near the end of the program, our whole team needed to process the last 3 months of results, but we were all getting consistently incorrect factors off when running our Mathematica notebooks. Five hours later someone discovered that one of the variables contained a stray Unicode whitespace or null character (or maybe a non-Unicode blank Mathematica object, such as a Graphics object with 0 area) that someone must have accidentally spawned somehow before saving and distributed the notebook to the rest of the team. Since Mathematica didn't recognize it as spacing but as part of the variable name, making it a different variable, the result of our integrals were incorrect. E.g. the integral of x^2 is x^3/3, but the integral of xx' is x^2x'/2, so the multiplier would be off by a factor of 3/2. After discovering and selecting it, we "cut" it into the clipboard, pasted it into another Mathematica notebook, saved it, and it was never opened again.