```\nfunction incentivize(\n address sender,\n address receiver, \n address operator,\n uint amountIn\n) external override onlyFei {\n    updateOracle();\n\n if (isPair(sender)) {\n  incentivizeBuy(receiver, amountIn);\n }\n\n if (isPair(receiver)) {\n        require(isSellAllowlisted(sender) || isSellAllowlisted(operator), "UniswapIncentive: Blocked Fei sender or operator");\n  incentivizeSell(sender, amountIn);\n }\n}\n```\n