```\\nfunction _validateSenderAndPaymaster(bytes calldata initCode, address sender, bytes calldata paymasterAndData) external view {\\n    if (initCode.length == 0 && sender.code.length == 0) {\\n        // it would revert anyway. but give a meaningful message\\n        revert("AA20 account not deployed");\\n    }\\n    if (paymasterAndData.length >= 20) {\\n        address paymaster = address(bytes20(paymasterAndData[0 : 20]));\\n        if (paymaster.code.length == 0) {\\n            // it would revert anyway. but give a meaningful message\\n            revert("AA30 paymaster not deployed");\\n        }\\n    }\\n    // always revert\\n    revert("");\\n}\\n```\\n