code: public List<PlanNode> findAllAtOrBelow( Set<Type> typesToFind ) {
          return findAllAtOrBelow(Traversal.PRE_ORDER, typesToFind);
      }
docs: Find all of the nodes with one of the specified types that are at or below this node.
  
  @param typesToFind the types of node to find; may not be null
  @return the collection of nodes that are at or below this node that all have one of the supplied types; never null but
  possibly empty