code: public static function contains(Iterator $iterator, $element) : bool
      {
          while ($iterator->valid()) {
              if (Objects::equal($iterator->current(), $element)) {
                  return true;
              }
              $iterator->next();
          }
          return false;
      }
docs: Returns true if iterator contains element. The check based on {@link Objects::equal()}.
  
  @param Iterator $iterator
  @param $element
  @return boolean