# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 2014-11-05 13:00:48
# Node ID 70809438c6449df12cc9d6d8afef1a66db1c8134
# Parent  85c634ff395a3c626108b324567b6f11dfd2917d

transaction: document `tr.add`

diff --git a/mercurial/transaction.py b/mercurial/transaction.py
--- a/mercurial/transaction.py
+++ b/mercurial/transaction.py
@@ -142,6 +142,7 @@ class transaction(object):
 
     @active
     def add(self, file, offset, data=None):
+        """record the state of an append-only file before update"""
         if file in self.map or file in self._backupmap:
             return
         if self._queue: