Function add_agent_random 

pub fn add_agent_random<S, A, Store, Props, R, Sch>(
    model: &mut StandardModel<S, A, Store, Props, R, Sch>,
    agent: A,
) -> Result<(), InteractionError<S::Error>>
where
    A: PositionedAgent,
    S: SpaceInteraction<A>,
    Store: AgentStore<A>,
    R: RngCore,
    Sch: Scheduler<StandardModel<S, A, Store, Props, R, Sch>>,

Add an agent to the model at a random position in the space.

The agent must not already exist in the store. If the space rejects the position, returns InteractionError::Space.