diff --git a/src/textual/widgets/_tree.py b/src/textual/widgets/_tree.py
index b7ea614db..27f28b034 100644
--- a/src/textual/widgets/_tree.py
+++ b/src/textual/widgets/_tree.py
@@ -1,3 +1,5 @@
+"""Provides a tree widget."""
+
 from __future__ import annotations
 
 from dataclasses import dataclass