/// <summary>
    /// This method tries to change the state the FSM is in based on
    /// the current state and the transition passed. If current state
    ///  doesn't have a target state for the transition passed, 
    /// an ERROR message is printed.
    /// </summary>
    public void PerformTransition(SimpleAITransition trans)
    {
        // Check for NullTransition before changing the current state
        if (trans == SimpleAITransition.NullTransition)
        {
            Debug.LogError("FSM ERROR: NullTransition is not allowed for a real transition");
            return;
        }

        // Check if the currentState has the transition passed as argument
        SimpleAIStateID id = currentState.GetOutputState(trans);
        if (id == SimpleAIStateID.NullStateID)
        {
            Debug.LogError("FSM ERROR: State " + currentStateID.ToString() +  " does not have a target state " +
                           " for transition " + trans.ToString());
            return;
        }

        // Update the currentStateID and currentState
        currentStateID = id;
        foreach (SimpleAIFSMState state in states)
        {
            if (state.ID == currentStateID)
            {
                // Do the post processing of the state before setting the new one
                currentState.DoBeforeLeaving();

                currentState = state;

                // Reset the state to its desired condition before it can reason or act
                currentState.DoBeforeEntering();
                break;
            }
        }
    }
    /// <summary>
    /// This method places new states inside the FSM,
    /// or prints an ERROR message if the state was already inside the List.
    /// First state added is also the initial state.
    /// </summary>
    public void AddState(SimpleAIFSMState s)
    {
        // Check for Null reference before deleting
        if (s == null)
        {
            Debug.LogError("FSM ERROR: Null reference is not allowed");
        }

        // First State inserted is also the Initial state,
        //   the state the machine is in when the simulation begins
        if (states.Count == 0)
        {
            states.Add(s);
            currentState = s;
            currentStateID = s.ID;
            return;
        }

        // Add the state to the List if it's not inside it
        foreach (SimpleAIFSMState state in states)
        {
            if (state.ID == s.ID)
            {
                Debug.LogError("FSM ERROR: Impossible to add state " + s.ID.ToString() +
                               " because state has already been added");
                return;
            }
        }
        states.Add(s);
    }