Sync fastapi docs from 50fa3f7c on 2026-01-11

docs_src/body/tutorial003_py39.py

@@ -0,0 +1,19 @@
+from typing import Union
+
+from fastapi import FastAPI
+from pydantic import BaseModel
+
+
+class Item(BaseModel):
+    name: str
+    description: Union[str, None] = None
+    price: float
+    tax: Union[float, None] = None
+
+
+app = FastAPI()
+
+
+@app.put("/items/{item_id}")
+async def update_item(item_id: int, item: Item):
+    return {"item_id": item_id, **item.model_dump()}