# HG changeset patch
# User Siddharth Agarwal <sid0@fb.com>
# Date 1426622775 25200
# Node ID 8a997bd734480f0039025e67afd3cdefa654edd8
# Parent  3e8b06097d00b8e22918ba9e6daf9613dd3a8229
patch.trydiff: add a docstring

It took me a bit to figure out what this function actually does.

diff -r 3e8b06097d00 -r 8a997bd73448 mercurial/patch.py
--- a/mercurial/patch.py	Tue Mar 17 15:33:34 2015 -0700
+++ b/mercurial/patch.py	Tue Mar 17 13:06:15 2015 -0700
@@ -2226,6 +2226,12 @@
 
 def trydiff(repo, revs, ctx1, ctx2, modified, added, removed,
             copy, getfilectx, opts, losedatafn, prefix):
+    '''given input data, generate a diff and yield it in blocks
+
+    If generating a diff would lose data like flags or binary data and
+    losedatafn is not None, it will be called.
+
+    prefix is added to every path in the diff output.'''
 
     def gitindex(text):
         if not text: