what?

module threadsafe.map;

synchronized class Map(TKey,TValue) {
    private:
    TValue[TKey] _map;

    public:
    void add(TKey key, TValue value) {
        _map[key] = value;
    }

    bool contains(TKey key) {
        return (key in _map) !is null;
    }

    @property int length() { return _map.length; }

    auto get(TKey key) {
        return _map.get(key, null);
    }

    void remove(TKey key) {
        if (contains(key)) {
            _map.remove(key);
        }
    }
}