class THLVisitor
	super Visitor
	var seen = new HashSet[String]
	redef fun visit(n)
	do
		var cn = n.class_name
		if not seen.has(cn) then
			seen.add cn

			var hl = new TestHighlightVisitor
			hl.highlight_node(n)
			print "<h2>AST node: {cn} at {n.location}</h2>"
			printn "<pre><code>"
			hl.html.write_to(stdout)
			print "</code></pre>"
		end

		n.visit_all(self)
	end
end