(PHP 5)
Can be used to iterate through recursive iterators.
$iterator
   [, int $mode = RecursiveIteratorIterator::LEAVES_ONLY
   [, int $flags = 0
  ]] )RecursiveIteratorIterator::LEAVES_ONLYRecursiveIteratorIterator::SELF_FIRSTRecursiveIteratorIterator::CHILD_FIRSTRecursiveIteratorIterator::CATCH_GET_CHILD