code: private static void printUsage(String cmd) {
      if ("-create".equals(cmd)) {
        System.err.println("Usage: java SnapshotShell [-create snapshot_id [-ignoreleases]]");
      } else if ("-list".equals(cmd)) {
        System.err.println("Usage: java SnapshotShell [-list]");
      } else if ("-delete".equals(cmd)) {
        System.err.println("Usage: java SnapshotShell [-delete snapshot_id]");
      } else {
        System.err.println("Usage: java SnapshotShell "
                           + "[-create snapshot_id [-ignoreleases]] "
                           + "[-list] "
                           + "[-delete snapshot_id] ");
      }
    }
docs: Displays format of commands.