public class FlagChecker
    {
        readonly Dictionary<string, bool> _flags = new Dictionary<string, bool>();

        public void Set(string flag, bool val)
        {
            OnFlagSet(flag, _flags[flag], val);
            _flags[flag] = val;
        }

        void OnFlagSet(string flag, bool old, bool newVal)
        {
            OnFlagChanged(flag,newVal);
        }

        public bool IsTrue(string flag) => _flags[flag];
        public bool IsFalse(string flag) => !_flags[flag];

        public bool this[string flag]
        {
            get => _flags[flag];
            set => SetFalse(flag);
        }

        public void SetTrue(string flag) => Set(flag,true);
        public void SetFalse(string flag) => Set(flag, false);

        public event Action<string, bool> FlagChanged;
        public event Action<string> FlagTrue;
        public event Action<string> FlagFalse;

        protected virtual void OnFlagChanged(string flag, bool val)
        {
            FlagChanged?.Invoke(flag, val);
            if (val) OnFlagTrue(flag);
            else OnFlagFalse(flag);
        }

        protected virtual void OnFlagTrue(string obj) => FlagTrue?.Invoke(obj);

        protected virtual void OnFlagFalse(string obj) => FlagFalse?.Invoke(obj);
    }