/**
  * @param string $s
  * @return string|null bcmath number
  * @throws \Exception
  */
 public static function parse($s)
 {
     //bcscale(2);
     $res = self::parsePrivate($s);
     if ($res === null) {
         return null;
     }
     return BigNumber::stripTrailingZeroes($res);
 }