```\naddress public constant ETH = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;\n\n// rest of code\n\n// Only need ability to check for read-only reentrancy for pools containing native Eth.\nif (checkReentrancy) {\n    if (tokens[0] != ETH && tokens[1] != ETH) revert MustHaveEthForReentrancy();\n}\n```\n