feature request/question: support the one dash as argument

[leha-bot]

Hello, I want to make a one dash as an argument (like gcc - for consuming stdin), but can't find anything about this, while I tried to create a simple argument, it fails with runtime exception.
May you help with this?

Thanks in advance for your attention, and thanks for your library, it's pretty cool! 😊

[jarro2783]

The parser probably thinks that it is starting an option and is invalid. I can fix that so that a standalone - is just read as a string.

[jarro2783]

What's the error? This works on the example program.