module traffic_light {
    // Define the states of the traffic light
    type state_t = enum { RED, GREEN };

    // Variable to store the current state of the traffic light
    var current_state : state_t;

    // Outputs indicating the status of the light
    output red : boolean;
    output green : boolean;

    // Initialize the traffic light to the RED state
    init {
        current_state = RED;
        red = true;
        green = false;
    }

    // Define the state transitions
    next {
        current_state' =
            if (current_state == RED) then GREEN
            else RED;

        red' = (current_state' == RED);
        green' = (current_state' == GREEN);
    }

    // Safety property: the traffic light cannot be both red and green
    invariant no_conflict : !(red && green);
}

// Main module to instantiate and simulate the traffic light
module main {
    instance tl : traffic_light;

    init {
        // Initialize the traffic light instance
    }

    next {
        // Transition to the next state of the traffic light
        next(tl);
    }
}
