"use two fixed columns and only 'group' rows in one of the columns"

dbbrooks

In this example: http://datatables.net/release-datatables/extras/FixedColumns/row_grouping_height.html, it is mentioned that "It would be readily possible to extend this example to use two fixed columns and only 'group' rows in one of the columns, potentially achieving quite a powerful effect."
I'd like to see an example of this where for example, the 1st column is grouped and the 2nd column isn't and both of them are frozen.
Does anyone have an example? Thanks!