public static String guessFileExtensionFromFormat(String format){
		switch(format.toUpperCase()){
		case "TURTLE":
			return "ttl";
		case "RDF/XML":
			return "rdf";
		case "N-TRIPLE":
			return "nt";
		case "N3":
			return "n3";
		default:
			return "txt";
			
		}
	}