Indentify expanded row index for row expander plugin

Hi,

I iam using grid row expnder plugin, while expand one row in that case call

expandbody : function (rowNode, record, expandRow) {} & while collaps call

collapsebody: function (rowNode, record, expandRow) {} but I want expanded row index & also at the time of collaps want collaps row index so please give me guide line for same?

Indentify expanded row index for row expander plugin