redef fun to_dot do
		var dot = new Buffer
		dot.append "{kind} \"{id}\" \{\n"
		if attrs.not_empty then dot.append attrs.to_dot(";\n")
		if nodes_attrs.not_empty then dot.append "node[{nodes_attrs.to_dot(",")}];\n"
		if edges_attrs.not_empty then dot.append "edge[{edges_attrs.to_dot(",")}];\n"
		for id, node in nodes do
			dot.append "{node.to_dot};\n"
		end
		for edge in edges do
			dot.append("{edge.to_dot};\n")
		end
		dot.append("\}")
		return dot
	end

	redef fun to_dot do
		var res = new Buffer
		res.append "\"{from.escape_id}\" "
		if directed then
			res.append "->"
		else
			res.append "--"
		end
		res.append " \"{to.escape_id}\" "
		if attrs.not_empty then res.append "[{attrs.to_dot(",")}]"
		return res.write_to_string
	end