<graphml>
     <key id="label" for="all" attr.name="label" attr.type="string"/>
     <key id="weight" for="node" attr.name="weight" attr.type="double"/>
     <graph edgedefault="directed">
          <node id="1">
                        <data key="label">A</data>
                        <data key="weight">2.0</data>
                    </node>
                    <node id="2">
                        <data key="label">B</data>
                        <data key="weight">1.5</data>
                    </node>
                    <node id="3">
                        <data key="label">C</data>
                        <data key="weight">1.0</data>
                    </node>
                    <edge source="1" target="2">
                        <data key="label">A to B</data>
                    </edge>
                    <edge source="1" target="3">
                        <data key="label">A to C</data>
                    </edge>
     </graph>
</graphml>