cpu

import hashlib

# Define a function to compute the hash of a block.
def compute_hash(block):
  # Encode the block data as a bytes object.
  block_bytes = str(block).encode()
  # Compute the SHA-256 hash of the block data.
  return hashlib.sha256(block_bytes).hexdigest()

# Define a function to mine a new block.
def mine_block(last_block, data):
  # Start with a random nonce value.
  nonce = 0
  # Compute the hash of the last block.
  last_hash = compute_hash(last_block)
  # Keep trying new nonce values until we find one that works.
  while True:
    # Compute the hash of the new block candidate.
    block_hash = compute_hash({
      'last_hash': last_hash,
      'data': data,
      'nonce': nonce
    })
    # Check if the block hash meets the difficulty requirement.
    if block_hash[:4] == '0000':
      # If it does, we've found a valid block.
      return {
        'last_hash': last_hash,
        'data': data,
        'nonce': nonce,
        'hash': block_hash
      }
    # If it doesn't, try the next nonce value.
    nonce += 1

# Define the starting block of the chain.
genesis_block = {
  'last_hash': '',
  'data': 'Genesis block',
  'nonce': 0,
  'hash': compute_hash({
    'last_hash': '',
    'data': 'Genesis block',
    'nonce': 0
  })
}

# Define the blockchain.
blockchain = [genesis_block]

# Mine some new blocks and add them to the chain.
for i in range(1, 10):
  new_block = mine_block(blockchain[-1], f'Block {i}')
  blockchain