code: public static function hrtime($asNum = false)
      {
          $ns = \microtime(false);
          $s = \substr($ns, 11) - self::$startAt;
          $ns = 1E9 * (float) $ns;
  
          if ($asNum) {
              $ns += $s * 1E9;
  
              return \PHP_INT_SIZE === 4 ? $ns : (int) $ns;
          }
  
          return array($s, (int) $ns);
      }
docs: @param bool $asNum
  
  @return array|float|int