CGAL 5.4.4  Quadtrees, Octrees, and Orthtrees

a traversal provides the functions needed to traverse the nodes of an orthtree.
A traversal is used to iterate on a tree with a userselected order (e.g. preorder, postorder).
Public Types  
using  Node = unspecified_type 
A specialization of CGAL::Orthtree<Traits,PointRange,PointMap>::Node.  
Public Member Functions  
Node  first (Node root) const 
returns the first node to iterate to, given the root of the Orthtree.  
Node  next (Node n) const 
returns the next node to iterate to, given the previous node.  