ERC777Reentrancy.sol

address token;
mapping(address => uint) canBorrowAmount;
/* Bad */
function badBorrow(uint amounts) public {
    require(amounts <= canBorrowAmount[msg.sender]); // 1.𝗖𝗛𝗘𝗖𝗞
    IERC777(token).transfer(msg.sender, amounts) // 3.𝗜𝗡𝗧𝗘𝗥𝗔𝗖𝗧𝗜𝗢𝗡
    canBorrowAmount[msg.sender] - amounts; // 2.𝗘𝗙𝗙𝗘𝗖𝗧𝗦
  }

/* Better */
function goodBorrow(uint amounts) public {
    require(amounts <= canBorrowAmount[msg.sender]); // 1.𝗖𝗛𝗘𝗖𝗞
    canBorrowAmount[msg.sender] - amounts; // 2.𝗘𝗙𝗙𝗘𝗖𝗧𝗦
    IERC777(token).transfer(msg.sender, amounts) // 3.𝗜𝗡𝗧𝗘𝗥𝗔𝗖𝗧𝗜𝗢𝗡
  }