k-anonymity metric, used for analysis of reidentification risk.
Optional message indicating that multiple rows might be
associated to a single individual. If the same entity_id is
associated to multiple quasi-identifier tuples over distinct
rows, we consider the entire collection of tuples as the
composite quasi-identifier. This collection is a multiset: the
order in which the different tuples appear in the dataset is
ignored, but their frequency is taken into account. Important
note: a maximum of 1000 rows can be associated to a single
entity ID. If more rows are associated with the same entity
ID, some might be ignored.