Unknown unknowns. My coding style hasn't really changed in years - frankly, I don't write a lot of code, I do other things. But I often run into situations whe

Unknown unknowns. My coding style hasn't really changed in years - frankly, I don't write a lot of code, I do other things. But I often run into situations where I'm irritated at my own bad code from months earlier, when the shortcomings of the code are actually driven by things I know now that I didn't know then.