* It also handles the conversion of voiced and semi-voiced sound marks.
 *
 * <p>This class provides the following functionalities:</p>
 * <ul>
 *   <li>Normalization of a string containing Hankaku Kana to Zenkaku Kana.</li>
 *   <li>Conversion of individual Hankaku Kana characters to Zenkaku Kana characters.</li>
 *   <li>Handling of voiced (ﾞ) and semi-voiced (ﾟ) sound marks to produce the correct Zenkaku Kana characters.</li>