public static Batch <Venue> nearbyCustomers(Target target, World world) {
    final Batch <Venue> sampled = new Batch <Venue> () ;
    world.presences.sampleFromKey(
      target, world, 5, sampled, Venue.class
    ) ;
    final Batch <Venue> returned = new Batch <Venue> () ;
    for (Venue v : sampled) {
      if (v.privateProperty()) continue ;
      if ((v instanceof SupplyDepot) || (v instanceof StockExchange)) continue ;
      returned.add(v) ;
    }
    return returned ;
  }