Function ax_timestamp_stn_to_unix_nanos 

pub fn ax_timestamp_stn_to_unix_nanos(
    seconds: i64,
    nanos: i64,
) -> Result<UnixNanos>

Converts AX ts (seconds) + tn (nanoseconds) fields to [UnixNanos].

Errors

Returns an error if seconds is negative (malformed data from AX).