assertEquals("test & test & test", htmlEscaper().escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", htmlEscaper().escape("test << 1"));
    assertEquals("test &gt;&gt; 1", htmlEscaper().escape("test >> 1"));
    assertEquals("&lt;tab&gt;", htmlEscaper().escape("<tab>"));

    // Test simple escape of '&'.
    assertEquals("foo&amp;bar", htmlEscaper().escape("foo&bar"));

    assertEquals("test & test & test", htmlEscaper().escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", htmlEscaper().escape("test << 1"));
    assertEquals("test &gt;&gt; 1", htmlEscaper().escape("test >> 1"));
    assertEquals("&lt;tab&gt;", htmlEscaper().escape("<tab>"));

    // Test simple escape of '&'.
    assertEquals("foo&amp;bar", htmlEscaper().escape("foo&bar"));

    assertEquals("xxx", xmlEscaper.escape("xxx"));
    assertEquals("test & test & test", xmlEscaper.escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", xmlEscaper.escape("test << 1"));
    assertEquals("test &gt;&gt; 1", xmlEscaper.escape("test >> 1"));
    assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"

    assertEquals("xxx", xmlEscaper.escape("xxx"));
    assertEquals("test & test & test", xmlEscaper.escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", xmlEscaper.escape("test << 1"));
    assertEquals("test &gt;&gt; 1", xmlEscaper.escape("test >> 1"));
    assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"

 * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
 *     implements Comparable&lt;FIFOEntry&lt;E&gt;&gt; {
 *   final static AtomicLong seq = new AtomicLong();
 *   final long seqNum;
 *   final E entry;
 *   public FIFOEntry(E entry) {
 *     seqNum = seq.getAndIncrement();

 * sorting with {@link java.util.Arrays#sort(double[]) Arrays.sort(double[])} or {@link
 * java.util.Collections#sort(java.util.List) Collections.sort(List<Double>)} and selecting
 * the required value(s). Those methods would sort {@link Double#NaN NaN} as if it is greater than
 * any other value and place them at the end of the dataset, even after {@link

 * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
 *     implements Comparable&lt;FIFOEntry&lt;E&gt;&gt; {
 *   final static AtomicLong seq = new AtomicLong();
 *   final long seqNum;
 *   final E entry;
 *   public FIFOEntry(E entry) {
 *     seqNum = seq.getAndIncrement();

 *       Stream.map}).
 *   <li><b>Do not</b> call {@link #doForward} or {@link #doBackward} directly; these exist only to
 *       be overridden.
 * </ul>
 *
 * <h3>Example</h3>
 *
 * <pre>
 *   return new Converter&lt;Integer, String&gt;() {
 *     protected String doForward(Integer i) {
 *       return Integer.toHexString(i);
 *     }
 *
 *     protected Integer doBackward(String s) {
 *       return parseUnsignedInt(s, 16);

 * "unescaping" the text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code
 * "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} from being confused with an XML tag. When the
 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *

 * text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code
 * "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} from being confused with an XML tag. When the
 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *