public static String dotVersion() throws IOException, InterruptedException {
		if (dotVersion == null) {
			if (GraphvizUtils.getDotExe() == null) {
				dotVersion = "Error: Dot not installed";
			} else if (GraphvizUtils.getDotExe().exists() == false) {
				dotVersion = "Error: " + GraphvizUtils.getDotExe().getAbsolutePath() + " does not exist";
			} else if (GraphvizUtils.getDotExe().isFile() == false) {
				dotVersion = "Error: " + GraphvizUtils.getDotExe().getAbsolutePath() + " is not a file";
			} else if (GraphvizUtils.getDotExe().canRead() == false) {
				dotVersion = "Error: " + GraphvizUtils.getDotExe().getAbsolutePath() + " cannot be read";
			} else {
				dotVersion = create(null, "png").dotVersion();
			}
		}
		return dotVersion;
	}