Update app.py

app.py

@@ -2,7 +2,7 @@ from datetime import datetime, timedelta
 from functools import partial
 from os import environ
 from typing import Callable, Coroutine
-
+from itertools import chain
 from anyio import create_task_group
 from fastapi import FastAPI, HTTPException, Request
 from fastapi.responses import HTMLResponse
@@ -153,7 +153,7 @@ async def proxy_openai_api(request: Request):
                     continue
                 else:
                     headers_to_forward = {k: v for k, v in headers.items() if k.lower() not in {'content-length', 'content-encoding', 'alt-svc'}}
-                    return OverrideStreamResponse(itertools.chain([first_chunk], response_generator), headers=headers_to_forward)
+                    return OverrideStreamResponse(chain([first_chunk], response_generator), headers=headers_to_forward)
             except StopAsyncIteration:
                 continue
         raise HTTPException(status_code=401, detail='все ключи API использованы, доступ запрещен.')