Method operator=

API/fleece/Mutable.hh:61–61

        keyref(Collection &coll, Key key)           :Value(coll.get(key)), _coll(coll), _key(key) { }
            template <class T>
        void operator= (const keyref &ref)          {_coll.set(_key, ref);}
            template <class T>
        void operator= (const T &value)             {_coll.set(_key, value);}
        void setData(slice value)                   {_coll.set(_key).setData(value);}