diff --git a/afutc/pieces.py b/afutc/pieces.py
index 61cf805..e4a979a 100644
--- a/afutc/pieces.py
+++ b/afutc/pieces.py
@@ -4,6 +4,8 @@ PIECES = [[[0, 1], [0, 1], [1, 1]], [[0, 1, 0], [1, 1, 1]], [[1, 1], [1, 1]],
           [[1, 1, 0], [0, 1, 1]], [[0, 1, 1], [1, 1, 0]], [[1], [1], [1], [1]],
           [[0, 1, 0], [0, 1, 0], [1, 1, 1]]]
 
+# To see the color number check this link:
+# https://i.stack.imgur.com/7AtMc.png
 __colors = [5, 7, 9, 11, 13, 15, 35, 41, 123, 205, 219]
 
 for n, piece in enumerate(PIECES):