The shell's big enough that I expect I'll be able to keep learning things about it for a long time, even though I've been writing shell scripts for ... lessee ... about 30 years.
I'm used to writing this:
case $key inwhatever) do-something ;;*) some-default-behavior ;;esac
I just read a Fedora system script that looks like this, instead:
case $key in(whatever) do-something ;;(*) some-default-behavior ;;esac
The leading paren is optional, but legal. And not just for bash, but for any POSIX shell. Amazing. Also, the last item doesn't have to have the semis, so it could even be this:
case $key in(whatever) do-something ;;(*) some-default-behavioresac