<gxl>
 <graph edgeids="true" edgemode="undirected">
  <node id="1"/>
  <node id="2"/>
  <node id="3"/>
  <node id="4"/>
  <node id="5"/>
  <edge id="e1" from="1" to="4"/>
  <edge id="e2" from="1" to="5"/>
  <edge id="e3" from="2" to="3"/>
  <edge id="e4" from="2" to="4"/>
 </graph>
</gxl>
