```\nFile: LimitOrderRegistry.sol\n    function claimOrder(uint128 batchId, address user) external payable returns (ERC20, uint256) {\n..SNIP..\n        // Transfer fee in.\n        address sender = _msgSender();\n        if (msg.value >= userClaim.feePerUser) {\n            // refund if necessary.\n            uint256 refund = msg.value - userClaim.feePerUser;\n            if (refund > 0) sender.safeTransferETH(refund);\n        } else {\n            WRAPPED_NATIVE.safeTransferFrom(sender, address(this), userClaim.feePerUser);\n            // If value is non zero send it back to caller.\n            if (msg.value > 0) sender.safeTransferETH(msg.value);\n        }\n```\n