Python 3's filter and map functions returns an iterator which you can't call len() on. Since we'll want to use len() later, we put the filter results into a tuple. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>