How to use custom tooltip for dojo-clusteredColumns chart, as we do in dojo-pie charts?

I am using dojo toolkit for generating charts. I have used dojo pie charts, where i gave custom tooltip as

  chart1.addSeries("Series 1", [{x:1,y:4,tooltip:"Value is 1"},
                                {x:2,y:6,tooltip:"Value is 2"}]);

Similarly, i want to use this feature in ClusteredBars/ClusteredColumns also. Please, Can anyone kindly suggest me how to give custom-tooltip in ClusteredBars开发者_StackOverflow中文版/ClusteredColumns type charts in dojo?

Thanks in advance, SuryaPavan

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chart1.addSeries("yourSerie", [ {
            y : $m0,
            tooltip : "the text to the serie"
        } ]);