* [your lang] std lib functions, their arg order. * HTTP status codes * Acronyms * Syntax mistakes (spot the bug). * Command line or vim snippets, e.g. "wri

* [your lang] std lib functions, their arg order. * HTTP status codes * Acronyms * Syntax mistakes (spot the bug). * Command line or vim snippets, e.g. "write a for loop over all files in a directory in bash" "grep and only show match" I find it most useful for catching things I commonly screw up. The trick, of course, is to build the habit of identifying when you've repeated a blunder and then to make it into a card. An example for this in Go would be using `range` and forgetting the second arg: `for val := range slice` is legal syntax, but `val` is actually the index var here, it should be `for _, val := range slice`.