Portfolio Margin Pro User Data Stream Connect

• The websocket base url is: wss://fstream.binance.com/pm-classic
• User Data Streams are accessed at /ws/
• Example: wss://fstream.binance.com/pm-classic/ws/XaEAKTsQSRLZAGH9tuIu37plSRsdjmlAVBoNYPUITlTAko1WI22PgmBMpI1rS8Yh
• The listenKey is generated using POST /fapi/v1/listenKey.