docs: def start_user_socket(self, callback):
          """Start a websocket for user data
  
          https://github.com/binance-exchange/binance-official-api-docs/blob/master/user-data-stream.md
  
          :param callback: callback function to handle messages
          :type callback: function
  
          :returns: connection key string if successful, False otherwise
  
          Message Format - see Binance API docs for all types
          """
          # Get the user listen key
          user_listen_key = self._client.stream_get_listen_key()
          # and start the socket with this specific key
          conn_key = self._start_user_socket(user_listen_key, callback)
          return conn_key