From 3a69c5f668b2214f6cb5583d9609a69358d337b5 Mon Sep 17 00:00:00 2001
From: Kazuhiro Masuda <kmasuda050@gmail.com>
Date: Mon, 21 Apr 2025 00:53:13 +0900
Subject: [PATCH] Update documentation

---
 docs/advanced-usage.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/docs/advanced-usage.md b/docs/advanced-usage.md
index 72b35016..7f252ead 100644
--- a/docs/advanced-usage.md
+++ b/docs/advanced-usage.md
@@ -138,6 +138,16 @@ steps:
 ```
 Please refer to the [Advanced range syntax section](https://github.com/npm/node-semver#advanced-range-syntax) of the [semver](https://github.com/npm/node-semver) to check other available range syntaxes.
 
+If you want to make an error when unspecified, set `PYTHON_VERSION_REQUIRED: true` to env.
+```yaml
+steps:
+- uses: actions/checkout@v4
+- uses: actions/setup-python@v5
+  env:
+    PYTHON_VERSION_REQUIRED: true
+  # the action fail with error.
+```
+
 ### Specifying a PyPy version
 The version of PyPy should be specified in the format `pypy<python_version>[-v<pypy_version>]` or `pypy-<python_version>[-v<pypy_version>]`.
 The `-v<pypy_version>` parameter is optional and can be skipped. The latest PyPy version will be used in this case.