*/
    void debug(CharSequence content);

    /**
     * Sends a message (and accompanying exception) to the user in the <b>debug</b> error level.
     * The error's stacktrace will be output when this error level is enabled.
     *
     * @param content the message to log
     * @param error the error that caused this log
     */
    void debug(CharSequence content, Throwable error);

    /**

     * @param elements the elements to join
     * @return elements separated by delimiter
     */
    public static String join(final CharSequence delimiter, final CharSequence... elements) {
        final StringBuilder sb = new StringBuilder();
        for (final CharSequence element : elements) {
            if (sb.length() > 0) {
                if (delimiter != null) {
                    sb.append(delimiter);

     */
    public StringSource(CharSequence content) {
        this(content, null);
    }

    /**
     * Creates a new source backed by the specified string.
     *
     * @param content The String representation, may be empty or {@code null}.
     * @param location The location to report for this use, may be {@code null}.
     */
    public StringSource(CharSequence content, String location) {

    @DisplayName("Should handle StringBuilder as CharSequence")
    void testJoinWithStringBuilder() {
        StringBuilder sb1 = new StringBuilder("first");
        StringBuilder sb2 = new StringBuilder("second");
        String result = StringUtil.join(",", sb1, sb2);
        assertEquals("first,second", result);
    }

    @Test
    @DisplayName("Should handle StringBuffer as CharSequence")
    void testJoinWithStringBuffer() {

    //
    // message building methods modelled after Ansi methods
    //

    @Nonnull
    @Override
    MessageBuilder append(CharSequence cs);

    @Nonnull
    @Override
    MessageBuilder append(CharSequence cs, int start, int end);

    @Nonnull
    @Override
    MessageBuilder append(char c);

    /**
     * Append content to the message buffer.
     *