Sync fastapi docs from 11614be9 on 2026-03-11

docs_src/sub_applications/tutorial001_py310.py

@@ -0,0 +1,19 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.get("/app")
+def read_main():
+    return {"message": "Hello World from main app"}
+
+
+subapi = FastAPI()
+
+
+@subapi.get("/sub")
+def read_sub():
+    return {"message": "Hello World from sub API"}
+
+
+app.mount("/subapi", subapi)