fn add_timestamp_tz_interval(
a: CheckedTimestamp<DateTime<Utc>>,
b: Interval,
) -> Result<CheckedTimestamp<DateTime<Utc>>, EvalError>fn add_timestamp_tz_interval(
a: CheckedTimestamp<DateTime<Utc>>,
b: Interval,
) -> Result<CheckedTimestamp<DateTime<Utc>>, EvalError>