public static Alias get(Catalog catalog, String aliasName) {
		HashSet<String> names = new HashSet<>();
		Alias alias = new Alias();
		Alias result = merge(alias, aliasName, catalog.aliases::get, names);
		return result.scriptRef != null ? result : null;
	}
Returns an Alias object for the given name. The given Catalog will be used
for any unqualified alias lookups.

@param catalog   A Catalog to use for lookups
@param aliasName The name of an Alias
@return An Alias object or null if no alias was found
src/main/java/dev/jbang/catalog/Alias.java