Yes, the Rosetta example seems to be outdated unfortunately, but one gets the idea.
You may also consider [https://nim-lang.org/docs/strscans.html](https://nim-lang.org/docs/strscans.html) or [https://nim-lang.org/docs/parseutils.html](https://nim-lang.org/docs/parseutils.html), that may be faster if you only wants to check if it is a number but you do not need the numerical value.
