public class NavmeshManager : INavigation
    {
        public bool LoadScene(Stream binaryData);
        public bool ClearScene();
        public bool FindPath(ref List path);
    }


    public interface INavigation
    {
        bool LoadScene(Stream binaryData);
        bool ClearScene();
        bool FindPath(ref List path);
    }


    public class NavigationManager
    {
        public void Init(INavigation implement)
        {
            _implement = implement;
        }


        public bool FindPath(ref List path)
        {
            return _implement.FindPathEx(ref path);
        }


        public static readonly NavigationManager Instance = new NavigationManager();
        private INavigation _implement = null;
    }


    public static class NavigationSafeOperation
    {
        public static bool FindPathEx(this INavigation navigation, ref List path)
        {
            if (navigation != null)
            {
                return navigation.FindPath(ref path);
            }
            else if (debugMode)
            {
                Console.Error.WriteLine("[INavigation.FindPathEx] navigation is null");
            }
            return false;
        }


        public static bool debugMode { get; set; }
    }