def METHOD_NAME(self, raw: bytes) -> None:
    msg = self._decoder_spot_order_book_partial_depth.decode(raw)
    instrument_id: InstrumentId = self._get_cached_instrument_id(
        msg.stream.partition("@")[0],
    )
    book_snapshot: OrderBookDeltas = msg.data.parse_to_order_book_snapshot(
        instrument_id=instrument_id,
        ts_init=self._clock.timestamp_ns(),
    )
    # Check if book buffer active
    book_buffer: Optional[list[Union[OrderBookDelta, OrderBookDeltas]]] = self._book_buffer.get(
        instrument_id,
    )
    if book_buffer is not None:
        book_buffer.append(book_snapshot)
    else:
        self._handle_data(book_snapshot)