There's a bug in his template.

He suggests to `set -eu`, which is a good idea, but then immediately does this:

    if [[ "$1" =~ ^-*h(elp)?$ ]]; ...

If the script is given no arguments, this will exit with an unbound variable error. Instead, you want something like this:

    if [[ "${1-}" =~ ^-*h(elp)?$ ]]; then