Removed unused variable definition in DFColumns.groupby
Removed unused variable definition in DFColumns.groupby

mjabri/holoviews,vascotenner/holoviews,basnijholt/holoviews,vascotenner/holoviews,ioam/holoviews,mjabri/holoviews,basnijholt/holoviews,ioam/holoviews,mjabri/holoviews,ioam/holoviews,basnijholt/holoviews,vascotenner/holoviews