diff --git a/telebot/callback_data.py b/telebot/callback_data.py
index 17bf27f..952030c 100644
--- a/telebot/callback_data.py
+++ b/telebot/callback_data.py
@@ -1,3 +1,11 @@
+# https://github.com/aiogram/aiogram/blob/dev-2.x/LICENSE
+"""
+This file was added during the pull request. The maintainers overlooked that
+it was copied "as is" from another project and they do not consider it as a 
+right way to develop a project. However, due to backward compatibility we had
+to leave this file in the project with the above copyright added,
+as it is required by the original project license.
+"""
 import typing