The one that annoyed me recently - numeric-looking string keys are turned into numeric keys. So if you have eg a hashmap of [naughty_word => replacement], then

The one that annoyed me recently - numeric-looking string keys are turned into numeric keys. So if you have eg a hashmap of [naughty_word => replacement], then [“penis”=>”willy”] and [“asshole”=>”bottom”] work fine, but [“69”=>”cuddle”] crashes your program with an "unexpected integer” exception.