A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that any involved record cannot be altered retroactively, without the alteration of all subsequent blocks.

I Developed a minimal version of blockchain using python which can accessed in below url:
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Github : <a href="https://github.com/erfaansabouri/blockchain-python">https://github.com/erfaansabouri/blockchain-python</a>