code: function unescape(str, type) {
    if (!isString(str)) return '';
    var chars = charSets[type || 'default'];
    var regex = toRegex(type, chars);
    return str.replace(regex, function(m) {
      return chars[m];
    });
  }
docs: Convert HTML entities to HTML characters.
  
  @param  {String} `str` String with HTML entities to un-escape.
  @return {String}