📝 Update source examples and docs from Python 3.9 to 3.10 (#14900)

docs_src/handling_errors/tutorial003_py310.py

@@ -0,0 +1,25 @@
+from fastapi import FastAPI, Request
+from fastapi.responses import JSONResponse
+
+
+class UnicornException(Exception):
+    def __init__(self, name: str):
+        self.name = name
+
+
+app = FastAPI()
+
+
+@app.exception_handler(UnicornException)
+async def unicorn_exception_handler(request: Request, exc: UnicornException):
+    return JSONResponse(
+        status_code=418,
+        content={"message": f"Oops! {exc.name} did something. There goes a rainbow..."},
+    )
+
+
+@app.get("/unicorns/{name}")
+async def read_unicorn(name: str):
+    if name == "yolo":
+        raise UnicornException(name=name)
+    return {"unicorn_name": name}