function changePrice(uint256 _tokenId, uint64 _priceGwei) external whenNotPaused {
        require(tokenContract.ownerOf(_tokenId) == msg.sender);
        uint256 lastIndex = latestAction[_tokenId];
        require(lastIndex > 0);
        Auction storage order = auctionArray[lastIndex];
        require(order.seller == msg.sender);
        require(order.tmSell == 0);

        uint64 tmNow = uint64(block.timestamp);
        require(order.tmStart + auctionDuration > tmNow);
        
        require(_priceGwei >= 1000000 && _priceGwei <= 999000000000);
        order.price = _priceGwei;

        AuctionPriceChange(lastIndex, msg.sender, _tokenId, _priceGwei);
    }