code: public function distance(array $a, array $b): float
      {
          if (count($a) !== count($b)) {
              throw InvalidArgumentException::arraySizeNotMatch();
          }
          $distance = 0;
          $count = count($a);
          for ($i = 0; $i < $count; ++$i) {
              $distance += pow($a[$i] - $b[$i], 2);
          }
          return sqrt((float) $distance);
      }
docs: @param array $a
  @param array $b
  
  @return float
  
  @throws InvalidArgumentException