When creating an ActionGroup to send a message to a set of agents, it is useful to indicate to Swarm whether that set is intended to be homogeneous or heterogeneous.
Faced with a heterogeneous set of agents, the process of method dispatch must occur over and over again. However, since the method implementation is the same for a homogeneous set, Swarm can exploit that.
Example (foil12.html#N476)
(It is also good for conceptual clarity to state the intended status of a mapping over a set of agents.)