[ move-up-slow(slow_elevator, current_floor, higher_floor)   move-down-slow(slow_elevator, current_floor, lower_floor)   move-up-fast(fast_elevator, current_floor, higher_floor)   move-down-fast(fast_elevator, current_floor, lower_floor)   board(passenger, elevator, floor, current_capacity, new_capacity)   leave(passenger, elevator, floor, current_capacity, previous_capacity) ]