```\n// Validate either on the first fill or if the signature type requires\n// regular validation.\naddress makerAddress = order.makerAddress;\nif (orderInfo.orderTakerAssetFilledAmount == 0 ||\n    \_doesSignatureRequireRegularValidation(\n        orderInfo.orderHash,\n        makerAddress,\n        signature\n    )\n) {\n```\n