_tokenize_chinese_chars(text) {
        /* Adds whitespace around any CJK character. */
        const output = [];
        for (let i = 0; i < text.length; ++i) {
            const char = text[i];
            const cp = char.charCodeAt(0);
            if (is_chinese_char(cp)) {
                output.push(" ");
                output.push(char);
                output.push(" ");
            } else {
                output.push(char);
            }
        }
        return output.join("");
    }
Adds whitespace around any CJK (Chinese, Japanese, or Korean) character in the input text.

@param {string} text The input text to tokenize.
@returns {string} The tokenized text with whitespace added around CJK characters.