Highlight only the last node of a dojo tree using lastFocused method programatically

Question

How can I only highlight the last node of a dojo tree prpgramatically . For example : I want to highlight 'Egypt' of the hierarchy The Earth -->Africa-->Egypt programatically then how can I achieve that. I read in some dojo documents that there is a lastFocused property in the _onNodeFocus method of dojo which can help us fix this issue. Can someone suggest how to use this function for my below case as an example. I couldn't find much documentation or information about this function.

<div data-dojo-type="dojo/store/Memory" data-dojo-id="myStore">
    <!-- Create store with inlined data.
        For larger data sets should use dojo.store.JsonRest etc. instead of dojo.store.Memory. -->
    <script type="dojo/method">
         this.setData([
            { id: 'world', name:'The earth', type:'planet', population: '6 billion'},
            { id: 'AF', name:'Africa', type:'continent', population:'900 million', area: '30,221,532 sq km',
                    timezone: '-1 UTC to +4 UTC', parent: 'world'},
                { id: 'EG', name:'Egypt', type:'country', parent: 'AF' },
                { id: 'KE', name:'Kenya', type:'country', parent: 'AF' },
                    { id: 'Nairobi', name:'Nairobi', type:'city', parent: 'KE' },
                    { id: 'Mombasa', name:'Mombasa', type:'city', parent: 'KE' },
                { id: 'SD', name:'Sudan', type:'country', parent: 'AF' },
                    { id: 'Khartoum', name:'Khartoum', type:'city', parent: 'SD' },
            { id: 'AS', name:'Asia', type:'continent', parent: 'world' },
                { id: 'CN', name:'China', type:'country', parent: 'AS' },
                { id: 'IN', name:'India', type:'country', parent: 'AS' },
                { id: 'RU', name:'Russia', type:'country', parent: 'AS' },
                { id: 'MN', name:'Mongolia', type:'country', parent: 'AS' },
            { id: 'OC', name:'Oceania', type:'continent', population:'21 million', parent: 'world'},
            { id: 'EU', name:'Europe', type:'continent', parent: 'world' },
                { id: 'DE', name:'Germany', type:'country', parent: 'EU' },
                { id: 'FR', name:'France', type:'country', parent: 'EU' },
                { id: 'ES', name:'Spain', type:'country', parent: 'EU' },
                { id: 'IT', name:'Italy', type:'country', parent: 'EU' },
            { id: 'NA', name:'North America', type:'continent', parent: 'world' },
            { id: 'SA', name:'South America', type:'continent', parent: 'world' }
        ]);
    </script>
    <script type="dojo/method" data-dojo-event="getChildren" data-dojo-args="object">
         // Supply a getChildren() method to store for the data model where
         // children objects point to their parent (aka relational model)
         return this.query({parent: this.getIdentity(object)});
    </script>
</div>

<!-- Create the model bridging the store and the Tree -->
<div data-dojo-type="dijit/tree/ObjectStoreModel" data-dojo-id="myModel"
  data-dojo-props="store: myStore, query: {id: 'world'}"></div>

<!-- buttons to test Tree features -->
<button onclick="mytree.collapseAll();">
    Collapse all
</button>
<button onclick="mytree.expandAll();">
    Expand all
</button>
<button onclick="mytree.set('paths', [ ['world', 'AF', 'KE', 'Nairobi'], ['world', 'SA'] ] );">
    Select Nairobi, South America
</button>

<!-- Create the tree -->
<div data-dojo-type="dijit/Tree" data-dojo-id="mytree"
        data-dojo-props="model: myModel, autoExpand: true"></div>