public Matches isEmoji(char[] sequence, int start, int end) {
    if (start < 0 || start > end || end > sequence.length) {
      throw new ArrayIndexOutOfBoundsException(
              "start " + start + ", end " + end + ", length " + sequence.length);
    }

    if (sequence == null) {
      return Matches.POSSIBLY;
    }

    Node tree = root;
    for (int i = start; i < end; i++) {
      if (!tree.hasChild(sequence[i])) {
        return Matches.IMPOSSIBLE;
      }
      tree = tree.getChild(sequence[i]);
    }

    return tree.isEndOfEmoji() ? Matches.EXACTLY : Matches.POSSIBLY;
  }
Checks if the sequence of chars within the given bound indices contain an emoji.
@see #isEmoji(char[])
src/main/java/com/vdurmont/emoji/EmojiTrie.java