class {
    public State state;
    //enums cant take double values...
    public struct State
    {
        public const float IDLE = 0f;
        public const float WALKING = 0.5f;
        public const float RUNNING = 1f;
    }
    protected void Stop()
    {
        SetSpeed(State.IDLE);
    }
    protected void SetSpeed(float f)
    {
        agent.speed = f;
        if (agent.speed > 1f && agent.speed < 5f)
        {
            f = State.WALKING;
            agent.Resume();
        }
        else if (agent.speed > 5f)
        {
            f = State.RUNNING;
            agent.Resume();
        }
        else
        {
            f = State.IDLE;
            agent.Stop();
        }
    }
}