Several months ago I deleted a functions because we didn't think we needed it any more. Today I found out I was wrong but I couldn't remember when I deleted it or I could just check the commit and pull the function back in. In order to find the commit where the code was deleted you can use the following command:

$ git log -SfunctionNameHere
commit 60b42b9d06dc8a046d338fddf99548f056c2305c
Author: Scott Keck-Warren <warren5236@gmail.com>
Date:   Sun Mar 16 11:45:41 2014 -0400

    Renamed String class to StringObject

Then to see the code that was changed you can use:

$git show 60b42b9d06dc8a046d338fddf99548f056c2305c
diff --git a/PHPO/String.php b/PHPO/String.php
deleted file mode 100644
index f87926b..0000000
--- a/PHPO/String.php
+++ /dev/null
@@ -1,63 +0,0 @@
-<?php
-
-namespace PHPO;
-
-use PHPO\ArrayObject;
<snip>