PK_ERROR_code_t     PK_GROUP_ask_entities
(
--- received arguments ---
PK_GROUP_t          group,          --- group

--- returned arguments ---
int          *const n_entities,     --- number of entities (>=0)
PK_ENTITY_t **const entities        --- entities  (optional)
)


This function returns the set of entities contained in the given group.


The returned array entities is optional. If it is set to NULL, the function
will only return the number of entities in the group.