```\n    function zDeposit(address to) external payable onlyZauction {\n        ethbalance[to] = SafeMath.add(ethbalance[to], msg.value);\n        emit zDeposited(to, msg.value);\n    }\n\n    function zWithdraw(address from, uint256 amount) external onlyZauction {\n        ethbalance[from] = SafeMath.sub(ethbalance[from], amount);\n        emit zWithdrew(from, amount);\n    }\n```\n