[개발순서]

* npx hardhat init (프로젝트 생성)
    * ❗️ README.md가 있으면 생성이 안됨. 
* ChainBattle.sol 작성 
* Alchemy 에서 Polygon mumbai network project 생성
* .env 파일작성

[npm module]

* npm add @openzeppelin/contracts
* npm install dotenv --save
* npm install --save-dev @nomiclabs/hardhat-waffle 'ethereum-waffle@^3.0.0' @nomiclabs/hardhat-ethers 'ethers@^5.0.0'

[hardhat 명령어]

* npx hardhat compile
* npx hardhat run scripts/deploy.js --network mumbai
* npx hardhat verify --network mumbai <YOUR_SMARTCONTRACT_ADDRESS>
* npx hardhat verify --network mumbai 0xbF64135700AC4927dAa6dA84E3d8958cBb704d0e