Pasted

 """
 import datetime as date
import hashlib as hasher
import random
 # Users of the blockchain
users = ["Alice", "Bob", "Charlie", "You"]
 class Transaction:
    def __init__(self, sender, receiver, amount):
        self.sender = sender
        self.receiver = receiver
        self.amount = amount
 class Block:
    def __init__(self, index, timestamp, data, previous_hash, nonce):
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.previous_hash = previous_hash
        self.nonce = nonce
        self.hash = self.hash_block()
     def hash_block(self):
        sha = hasher.sha256()
        sha.update((str(self.index) + str(self.timestamp) + str(self.data) + str(self.nonce) + str(self.previous_hash)).encode())
        return sha.hexdigest()
 def create_genesis_block():
    return Block(0, date.datetime.now(), "Genesis Block", "0", 1)
 def next_block(last_block):
    this_index = last_block.index + 1
    this_timestamp = date.datetime.now()
     rnd = random.Random()
    user_transactions = users.copy()
    sender = rnd.choice(user_transactions)
    user_transactions.remove(sender)
    receiver = rnd.choice(user_transactions)
    amount = rnd.randint(1, 100)
     this_data = Transaction(sender, receiver, amount)
    previous_hash = last_block.hash
    this_nonce = proof_of_work(last_block.nonce, this_index, this_timestamp, this_data, previous_hash)
     return Block(this_index, this_timestamp, this_data, previous_hash, this_nonce)
 def proof_of_work(last_nonce, this_index, this_timestamp, this_data, previous_hash):
    incrementor = 0
    block = Block(this_index, this_timestamp, this_data, previous_hash, incrementor)
    while str(block.hash)[:4] != '0000':
        incrementor += 1
        block = Block(this_index, this_timestamp, this_data, previous_hash, incrementor)
    return incrementor
 # Initialize the blockchain
blockchain = [create_genesis_block()]
previous_block = blockchain[0]
 # Generate a number of blocks with fake transactions
num_of_blocks_to_add = 100
for i in range(num_of_blocks_to_add):
    block_to_add = next_block(previous_block)
    blockchain.append(block_to_add)
    previous_block = block_to_add
 # Calculate the balance of each user
balances = {user: 0 for user in users}
for block in blockchain:
    if block.index == 0:
        continue
    transaction = block.data
    balances[transaction.sender] -= transaction.amount
    balances[transaction.receiver] += transaction.amount
 # Display the balance of each user
for user, balance in balances.items():
    print(f"{user}'s balance: {balance}")