/** * A constructor that takes the user's ID. If the ID is null, or * longer than 32 characters, or it does not start with "@", * throw an IllegalArgumentException. * The ID may contain any ASCII...

/**
     * A constructor that takes the user's ID. If the ID is null, or
     * longer than 32 characters, or it does not start with "@",
     * throw an IllegalArgumentException.
     * The ID may contain any ASCII characters, so you don't have to
     * worry about checking for special characters. Also do not worry
     * about checking whether any other user has the same ID.
     *
     * All other instance variables should be initialized appropriately.
     *
     * @param userID the ID of the new user
     */
    public TwitterUser(String userID) {
        throw new UnsupportedOperationException("Implement this");
    }