function _burn(uint256 _tokenId) internal {
    require(_isApprovedOrOwner(msg.sender, _tokenId), 'caller is not owner nor approved');

    address owner = ownerOf(_tokenId);

    // Clear approval
    approve(address(0), _tokenId);
    // Remove token
    _removeTokenFrom(msg.sender, _tokenId);
    emit Transfer(owner, address(0), _tokenId);
}

function _removeTokenFrom(address _from, uint256 _tokenId) internal {
    // Throws if `_from` is not the current owner
    assert(idToOwner[_tokenId] == _from);
    // Change the owner
    idToOwner[_tokenId] = address(0);
    // Update owner token index tracking
    _removeTokenFromOwnerList(_from, _tokenId);
    // Change count tracking
    ownerToNFTokenCount[_from] -= 1;
}
    rewardToken.transfer(tokenowner, reward);
    if (tokenowner == address(0){
        rewardToken.transfer(treasury, reward);
        weth.transfer(treasury, rewardEth);
    }
