touched up comments in advanced map/reduce test

tests/queryset.py

@@ -696,8 +696,8 @@ class QuerySetTest(unittest.TestCase):
 
         # Note: Test data taken from a custom Reddit homepage on
         # Fri, 12 Feb 2010 14:36:00 -0600. Link ordering should
-        # reflect order of insertion below.
-
+        # reflect order of insertion below, but is not influenced
+        # by insertion order.
         Link(title = "Google Buzz auto-followed a woman's abusive ex ...",
              up_votes = 1079,
              down_votes = 553,
@@ -768,10 +768,14 @@ class QuerySetTest(unittest.TestCase):
             }
         """
 
+        # provide the reddit epoch (used for ranking) as a variable available
+        # to all phases of the map/reduce operation: map, reduce, and finalize.
         reddit_epoch = mktime(datetime(2005, 12, 8, 7, 46, 43).timetuple())
         scope = {'reddit_epoch': reddit_epoch}
 
-        # ensure both artists are found
+        # run a map/reduce operation across all links. ordering is set
+        # to "-value", which orders the "weight" value returned from
+        # "finalize_f" in descending order.
         results = Link.objects.order_by("-value")
         results = results.map_reduce(map_f,
                                      reduce_f,