Function parse_funding_rate_update 

pub fn parse_funding_rate_update(
    funding: &LighterFunding,
    instrument_id: InstrumentId,
    interval: Option<u16>,
    ts_init: UnixNanos,
) -> Result<FundingRateUpdate>

Parses a Lighter historical funding row into a Nautilus [FundingRateUpdate].

Lighter returns rate as a magnitude and direction as the side paying the funding. Nautilus uses the conventional signed rate: positive when longs pay shorts and negative when shorts pay longs.

Errors

Returns an error if the timestamp cannot be converted.