fn do_cohort_drift(
index: &dyn TemporalIndexAccess,
entity_ids: &[u64],
t1: i64,
t2: i64,
top_n: usize,
) -> Result<QueryResult, QueryError>fn do_cohort_drift(
index: &dyn TemporalIndexAccess,
entity_ids: &[u64],
t1: i64,
t2: i64,
top_n: usize,
) -> Result<QueryResult, QueryError>