From ee8d9a1312797071becbb9731c1abd9e066bbbfc Mon Sep 17 00:00:00 2001
From: Alexander Schepanovski <suor.web@gmail.com>
Date: Tue, 23 Apr 2019 17:02:15 +0700
Subject: [PATCH] dvc: improve apply_diff() docstring

- explain how it works and why is it needed
- fix typo
---
 dvc/utils/collections.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/dvc/utils/collections.py b/dvc/utils/collections.py
index 2d7b259fa..e1367d10a 100644
--- a/dvc/utils/collections.py
+++ b/dvc/utils/collections.py
@@ -8,7 +8,14 @@ def compact(args):
 
 
 def apply_diff(src, dest):
-    """Recursively apply changes from stc to dest"""
+    """Recursively apply changes from src to dest.
+
+    Preserves dest type and hidden info in dest structure,
+    like ruamel.yaml leaves when parses files. This includes comments,
+    ordering and line foldings.
+
+    Used in Stage load/dump cycle to preserve comments and custom formatting.
+    """
     Seq = (list, tuple)
     Container = (Mapping, list, tuple)