Function aggregate 

pub fn aggregate(
    tx: &mut Transaction,
    global_id: &str,
    parent: EntityId,
    children: &[EntityId],
) -> SpatialAuthoringResult<EntityId>

Stage an IfcRelAggregates: a container decomposed into parts.

IFC4 and IFC4X3 only: it writes their layout and leaves OwnerHistory $, which IFC2X3 requires. In IFC2X3 use aggregate_with_owner_history, which binds the model’s declared release.

Errors

Refuses a malformed GlobalId, an empty child list, and a parent listed among its own children.