improve comment

diff --git a/Lib/datetime.py b/Lib/datetime.py
index b64637f2d4db080063a846e4e54dc754459764a2..1789714034c97fd3333e4c9d27cf2caebbc29f02 100644 (file)
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -23,10 +23,10 @@ _MAXORDINAL = 3652059 # date.max.toordinal()
 # for all computations.  See the book for algorithms for converting between
 # proleptic Gregorian ordinals and many other calendar systems.
 
-# -1 is a placeholder for 0.
+# -1 is a placeholder for indexing purposes.
 _DAYS_IN_MONTH = [-1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
 
-_DAYS_BEFORE_MONTH = [-1] # -1 is a placeholder for 0.
+_DAYS_BEFORE_MONTH = [-1] # -1 is a placeholder for indexing purposes.
 dbm = 0
 for dim in _DAYS_IN_MONTH[1:]:
     _DAYS_BEFORE_MONTH.append(dbm)