This is probably the best mini implementation I've seen so far. The code is hosted at https://github.com/Haseeb-Qureshi/lets-build-a-blockchain

He's missed one thing though, which a lot of these small implmentations miss, its the code for chain re-org.

https://en.bitcoin.it/wiki/Chain_Reorganization

This is a crucial piece of code that figures out which chain is correct if 1 or more blocks arrive that have a greater proof of work than your current best chain.

But otherwise, a very good attempt.

I want to see "let's build a blockchain" minus the cryptocurrency. My understanding was that Medical and Financial institutions were more interested in the ledger not so much the currencies behind bitcoin and other cryptocurrencies. Or am I looking at this all wrong?

Here's an earlier example I found, building a tiny blockchain in Python: https://hackernoon.com/learn-blockchains-by-building-one-117....

Long, but accessible introduction. "The fastest way to learn how Blockchains work is to build one."

wanna learn it