diff --git a/dijkstra.py b/dijkstra.py
index 4db4009c9893a1c7c9a37cd0176c7e3d6f48919f..26f0a3d8584b0cc1d29e69d68837a0a8139410cb 100644
--- a/dijkstra.py
+++ b/dijkstra.py
@@ -1,3 +1,4 @@
+"""Python >= 3.12 minimum."""
 import heapq
 from pprint import pprint
 from collections import defaultdict