(PHP 5 >= 5.3.0, PHP 7)
Allows iterating over a RecursiveIterator to generate an ASCII graphic tree.
$it
   [, int $flags = RecursiveTreeIterator::BYPASS_KEY
   [, int $cit_flags = CachingIterator::CATCH_GET_CHILD
   [, int $mode = RecursiveIteratorIterator::SELF_FIRST
  ]]] )$iterator
   [, int $mode = RecursiveIteratorIterator::LEAVES_ONLY
   [, int $flags = 0
  ]] )RecursiveTreeIterator::BYPASS_CURRENT
RecursiveTreeIterator::BYPASS_KEY
RecursiveTreeIterator::PREFIX_LEFT
RecursiveTreeIterator::PREFIX_MID_HAS_NEXT
RecursiveTreeIterator::PREFIX_MID_LAST
RecursiveTreeIterator::PREFIX_END_HAS_NEXT
RecursiveTreeIterator::PREFIX_END_LAST
RecursiveTreeIterator::PREFIX_RIGHT
