>>> diff.py out_dir_a out_dir_b
Only in out_dir_a: only_in_a
Only in out_dir_b: only_in_b
--- out_dir_a/output.txt
+++ out_dir_b/output.txt
@@ -1,5 +1,5 @@
 Hello!
 {
-    "id": "[USERID]",
+    "id": "[UUID]",
     "userName": "[USERNAME]"
 }