* @return the stripe at the specified index
   */
  public abstract L getAt(int index);

  /**
   * Returns the index to which the given key is mapped, so that getAt(indexFor(key)) == get(key).
   */
  abstract int indexFor(Object key);

  /** Returns the total number of stripes in this instance. */
  public abstract int size();

  /**

        suggester.indexer().indexFromDocument(new Map[] { Collections.singletonMap(field, (Object) "この柿は美味しい。") });
        suggester.indexer().addElevateWord(elevateWord, true);
        suggester.refresh();

        Thread.sleep(1000);
        ZonedDateTime threshold = ZonedDateTime.now();
        Thread.sleep(1000);

        if (buf.indexOf("dd") == -1) {
            final int pos = buf.indexOf("d");
            if (pos != -1) {
                buf.replace(pos, pos + 1, "dd");
            }
        }
        if (buf.indexOf("HH") == -1) {
            final int pos = buf.indexOf("H");
            if (pos != -1) {
                buf.replace(pos, pos + 1, "HH");
            }
        }
        if (buf.indexOf("mm") == -1) {

    assertThat(Bytes.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 2, (byte) 3})).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 3, (byte) 4})).isEqualTo(1);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 3})).isEqualTo(1);

    assertThat(iia.indexOf(1)).isEqualTo(0);
    assertThat(iia.indexOf(8)).isEqualTo(5);
    assertThat(iia.indexOf(4)).isEqualTo(-1);
    assertThat(ImmutableDoubleArray.of(13).indexOf(13)).isEqualTo(0);
    assertThat(ImmutableDoubleArray.of().indexOf(21)).isEqualTo(-1);
    assertThat(iia.subArray(1, 5).indexOf(1)).isEqualTo(0);
  }

  public void testIndexOf_specialValues() {

    assertThat(Doubles.indexOf(ARRAY234, EMPTY)).isEqualTo(0);
    assertThat(Doubles.indexOf(EMPTY, ARRAY234)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY234, ARRAY1)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY1, ARRAY234)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Doubles.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);

    assertThat(Chars.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 2, (char) 3})).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 3, (char) 4})).isEqualTo(1);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 3})).isEqualTo(1);

  }

  public void testIndexOf() {
    assertThat(Ints.indexOf(EMPTY, (int) 1)).isEqualTo(-1);
    assertThat(Ints.indexOf(ARRAY1, (int) 2)).isEqualTo(-1);
    assertThat(Ints.indexOf(ARRAY234, (int) 1)).isEqualTo(-1);
    assertThat(Ints.indexOf(new int[] {(int) -1}, (int) -1)).isEqualTo(0);
    assertThat(Ints.indexOf(ARRAY234, (int) 2)).isEqualTo(0);
    assertThat(Ints.indexOf(ARRAY234, (int) 3)).isEqualTo(1);

);

suggester.indexer()
    .indexFromDocument(reader, 2, 100)  // threads=2, batch=100
    .getResponse();
```

### Index from Query Logs

```java
import org.codelibs.fess.suggest.index.contents.querylog.QueryLog;

// Add suggestions from search query logs
QueryLog queryLog = new QueryLog("user search query", "user123");
suggester.indexer().indexFromQueryLog(queryLog);
```

    assertThat(Doubles.indexOf(ARRAY234, EMPTY)).isEqualTo(0);
    assertThat(Doubles.indexOf(EMPTY, ARRAY234)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY234, ARRAY1)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY1, ARRAY234)).isEqualTo(-1);
    assertThat(Doubles.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Doubles.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);