pub fn parse_futures_ws_book_delta(
delta: &KrakenFuturesBookDelta,
instrument: &InstrumentAny,
sequence: u64,
ts_init: UnixNanos,
) -> Result<OrderBookDelta>pub fn parse_futures_ws_book_delta(
delta: &KrakenFuturesBookDelta,
instrument: &InstrumentAny,
sequence: u64,
ts_init: UnixNanos,
) -> Result<OrderBookDelta>