diff --git a/book/external/Useful_python_code b/book/external/Useful_python_code
index c8327b3..8c7d765 160000
--- a/book/external/Useful_python_code
+++ b/book/external/Useful_python_code
@@ -1 +1 @@
-Subproject commit c8327b3e2cc68d44958974a47c940bc89f4bb32b
+Subproject commit 8c7d765f3a06b18517b315455ae7f5dc9230748c