<root>
    <a>
        <user>
            <name>Mariano</name>
            <lastName>de Achaval</lastName>
        </user>
        <user>
            <name>Luis</name>
            <lastName>de Bello</lastName>
        </user>
    </a>
    <b>
        <user age="31" name="Mariano" sex="male"/>
        <user age="35" name="Paula" sex="female"/>
    </b>
</root>