In the manual it doesn't say that you can create your own custom exceptions. Personally, I prefer to create my own so that I am clear whether it is from nim's code or mine. Someone has shown how to create custom exceptions: [https://forum.nim-lang.org/t/2863#17814](https://forum.nim-lang.org/t/2863#17814) I think something like this ought to be in the Exceptions section of the manual.
