1. Upgrade Box -> BoxV2
2. Initially, Proxy -> Box
3. Later, Proxy -> BoxV2

2 options to create Proxy contract:

1. Manually: SmallProxy - sublesson
2. Hardhat's deploy() in-built proxies:
   • without any modification of the contract itself,
   • but ensuring that all the constructor args have been passed in proxy init/update f(),
   • setting {proxy: true} in the same deploy f()
3. Openzeppelin: Upgrade plugins (scripts)