template <class TKey>
class KHashTableIterator : public std::iterator<std::forward_iterator_tag, KHashTable<TKey> >
{
    friend class KHashTable<TKey>;
protected:
    KHashTable<TKey>& data;
    int ind;
public:
    KHashTableIterator<TKey>(KHashTable<TKey> &d, int i) : data(d), ind(i) {};
    TKey& operator *(){
        return data.table[ind];
    }
    KHashTableIterator<TKey>& operator ++(){
        ind++;
        while (!isUsed[ind])
            ind++;
        return *this;
    }
    KHashTableIterator<TKey>& operator ++(int a){
        ind++;
        while (!data.isUsed[ind])
            ind++;
        return *this;
    }
    bool operator ==(KHashTableIterator<TKey> &it){
        return (data == it.data && ind == it.ind);
    }
    bool operator !=(KHashTableIterator<TKey>&it){
        return !(*this == it);
    }
};