Blockchain

blockchain.py

import hashlib

blockchain = []
difficulty = 3
mine_pattern = '0' * difficulty

def add_block(data):
        block = make_block(data)
        block['prev'] = '' if blockchain == [] else blockchain[-1]['hash']
        mine_block(block)
        blockchain.append(block)

def make_block(data):
        return {'data': data, 'nonce': 0}

def mine_block(block):
        while not is_block_mined(block):
                block['nonce'] += 1
        block['hash'] = hash_block(block)

def is_block_mined(block):
        return mine_pattern == hash_block(block)[:difficulty]

def hash_block(block):
        return hash(f'{block["data"]}{block["nonce"]}{block["prev"]}')

def hash(str):
        return hashlib.sha256(str.encode()).hexdigest()

# Test Blockchain
add_block('First block')
add_block('Second block')
for i in range(len(blockchain)):
        print(blockchain[i])