I found the following YouTube short on the official Solana channel: https://www.youtube.com/watch?v=-hvCSuCauCA

At 0:20 min you can see a part of his code where he uses a BlockHash function. Unfortunately I'm not able to find anything about this function. Neither in the docs (https://solana-labs.github.io/solana-web3.js/) nor when I search the repository on Github.

Does someone know where I can find more information about this function?

I found the following YouTube short on the official Solana channel.

At 0:20 min you can see a part of his code where he uses and caches the result from the BlockHash function. 

Unfortunately, I'm not able to find anything about this function. Neither in the docs nor when I search the repository on GitHub.

Does someone know where I can find more information about this function?