```python
        from fastapi import APIRouter, FastAPI, WebSocket

        app = FastAPI()
        router = APIRouter()

        @router.websocket("/ws")
        async def websocket_endpoint(websocket: WebSocket):
            await websocket.accept()
            while True:
                data = await websocket.receive_text()
                await websocket.send_text(f"Message text was: {data}")

        **Example**

        ```python
        from fastapi import FastAPI, WebSocket

        app = FastAPI()

        @app.websocket("/ws")
        async def websocket_endpoint(websocket: WebSocket):
            await websocket.accept()
            while True:
                data = await websocket.receive_text()
                await websocket.send_text(f"Message text was: {data}")