message: attempt to fix a SFINAE build error
diff: @@ -436,9 +436,7 @@ namespace ospray {
  ctx.level--;
  }
  - template <
  - typename VISITOR_T,
  - typename = ospcommon::traits::is_base_of_t<VISITOR_T, Visitor>>
  + template <typename VISITOR_T, typename>
  inline void Node::traverse(VISITOR_T &&visitor)
  {
  TraversalContext ctx;
  