I am currently implementing ERC721 as the standard for token-exchange in the game I am programming. I am taking inspiration from the CryptoKitties-smart contract. One thing I have realized, is that the code smart contract I am currently reading is an implementation for solidity v0.4.11, as seen here: https://gist.github.com/arpit/071e54b95a81d13cb29681407680794f
I could not find any newer version. In this version, they implement a version of ERC721 that is not up to date. One of the things missing is approveForAll, and the concept of having one account being operated by another. Is it not required to implement this? And if it is, do I have to make it functional, or can I simply make it a function that doesnt have any proper implementation?