@SafeVarargs
	public static <T> Cfg<T> of(final Rule<? extends T>... rules) {
		return Cfg.of(List.of(rules));
	}
Create a grammar object with the given rules.

@param rules the rules the grammar consists of
@throws IllegalArgumentException if the list of rules is empty or there
        are duplicate rules
@throws NullPointerException if the list of rules is {@code null}
jenetics.ext/src/main/java/io/jenetics/ext/grammar/Cfg.java