docs: function translateFormat(formatString, mapping) {
    let len = formatString.length,
      i = 0,
      beginIndex = -1,
      lastChar = null,
      currentChar = "",
      resultString = "";
  
    for (; i < len; i++) {
      currentChar = formatString.charAt(i);
  
      if (lastChar === null || lastChar !== currentChar) {
        // change detected
        resultString = _appendMappedString(formatString, mapping, beginIndex, i, resultString);
  
        beginIndex = i;
      }
  
      lastChar = currentChar;
    }
  
    return _appendMappedString(formatString, mapping, beginIndex, i, resultString);
  }