pub fn parse_futures_ws_mark_price(
ticker: &KrakenFuturesTickerData,
instrument: &InstrumentAny,
ts_init: UnixNanos,
) -> Option<MarkPriceUpdate>pub fn parse_futures_ws_mark_price(
ticker: &KrakenFuturesTickerData,
instrument: &InstrumentAny,
ts_init: UnixNanos,
) -> Option<MarkPriceUpdate>