Constant BINANCE_SPOT_SBE_WS_API_DEMO_URL 

pub const BINANCE_SPOT_SBE_WS_API_DEMO_URL: &str = "wss://demo-ws-api.binance.com/ws-api/v3?responseFormat=sbe&sbeSchemaId=3&sbeSchemaVersion=3";

Binance Spot SBE WebSocket API URL (demo).