{alt1,...} any of the comma-separated alternatives - to avoid conflict with the block specification, patterns with curly-braces should be enclosed in quotes

Couldn't find any instance of this syntax in examples or tests. I assumed it should work like this but it throws an error:

**/*.{c,h} {
	prep: make test
}
17:29:27: Error reading config file ./modd.conf: ./modd.conf:1: unknown directive: c

Please provide an example or clarify how it is meant to be used.

Thank you.