From 9d2481bedf905fbca566d99a8abfce9892a692e4 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 6 Dec 2013 21:42:36 -0500
Subject: [PATCH] [subset] Comments

---
 Lib/fontTools/subset.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Lib/fontTools/subset.py b/Lib/fontTools/subset.py
index 05ca2326e..966afb46f 100644
--- a/Lib/fontTools/subset.py
+++ b/Lib/fontTools/subset.py
@@ -1067,9 +1067,12 @@ def subset_feature_tags(self, feature_tags):
 @_add_method(ttLib.getTableClass('GSUB'),
              ttLib.getTableClass('GPOS'))
 def prune_pre_subset(self, options):
+  # Drop undesired features
   if '*' not in options.layout_features:
     self.subset_feature_tags(options.layout_features)
+  # Drop unreferenced lookups
   self.prune_lookups()
+  # Prune lookups themselves
   if self.table.LookupList:
     self.table.LookupList.prune_pre_subset(options);
   return True
@@ -1082,6 +1085,7 @@ def prune_post_subset(self, options):
     table.ScriptList = None
   if table.FeatureList and not table.FeatureList.FeatureRecord:
     table.FeatureList = None
+  # Prune lookups themselves
   if table.LookupList:
     table.LookupList.prune_post_subset(options);
     if not table.LookupList.Lookup: