`EventSource` clients. Useful for keep-alive pings to prevent
            proxy/load-balancer timeouts.
            """
        ),
    ] = None

    @model_validator(mode="after")
    def _check_data_exclusive(self) -> "ServerSentEvent":
        if self.data is not None and self.raw_data is not None:
            raise ValueError(
                "Cannot set both 'data' and 'raw_data' on the same "