I agree it can be domain-specific, but I think it's more common than not that empty containers, and the number zero, are corner cases rather than typical values

I agree it can be domain-specific, but I think it's more common than not that empty containers, and the number zero, are corner cases rather than typical values. So I think it would be a decent quality-of-life improvement to make generators of the sort you suggest easily available, and have the tutorial docs use them from the start.