// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.16 <0.8.0;
// 子合约会继承多个父合约的属性和方法 
// 多继承时，父合约有相同同属笥时，按is后的继承顺序继承，后继承的会覆盖前面对象的属性
contract Father{
    uint public money = 0;
    address public owner;
    function increment() public {
        money += 10;
    }
    constructor() public {
        owner = msg.sender;
    }
    modifier check(){
        require(msg.sender == owner, "no auth !");
        _;
    }
    function kill() public check{
        selfdestruct(owner);
    }
}