fn date_diff_timestamp(
unit: &str,
a: CheckedTimestamp<NaiveDateTime>,
b: CheckedTimestamp<NaiveDateTime>,
) -> Result<i64, EvalError>fn date_diff_timestamp(
unit: &str,
a: CheckedTimestamp<NaiveDateTime>,
b: CheckedTimestamp<NaiveDateTime>,
) -> Result<i64, EvalError>