*
     * @param args CLI args
     * @param workingDirectory working directory
     * @param stdout stdout
     * @param stderr stderr
     * @return return code
     */
    public int doMain(String[] args, String workingDirectory, PrintStream stdout, PrintStream stderr) {
        PrintStream oldout = System.out;
        PrintStream olderr = System.err;

        final Set<String> realms;

		case *rsa.PrivateKey:
			return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
		case *ecdsa.PrivateKey:
			b, err := x509.MarshalECPrivateKey(k)
			if err != nil {
				fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
				os.Exit(2)
			}
			return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
		default:
			return nil
		}
	}

	var priv any
	var err error