protected NS unionStream(Stream<NS> shapes) {
		return shapes.reduce(BoundingShape::unionBounds).orElse(null);
	}
Called when a node is finished being visited.

This only applies to nodes into which the visitor descends. The visitor will finish a
node in one of three ways: 1) The node's children have all been visited. 2) The visitor
returned {@link VisitResult#TERMINATE} while visiting a descendant. 3) The visitor
returned {@link VisitResult#ASCEND} while visiting a child.

This method may return any result except {@link VisitResult#DESCEND}. If the visitor is
terminating, the return value of this method is ignored.

@param parent the parent of this node, or {@code null} when visiting the root
@param n the node currently being visited
@param inclusion the original inclusion of the query before descending
@return a directive for how the visitor should proceed
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/spatial/AbstractConstraintsTree.java