input: Write a function to implement a simple blockchain system in Python. The function should define a Block class that represents a block in the blockchain, a method to create a new block with a hash based on its contents, a function to create the blockchain starting from a genesis block, and a function to print the blockchain. 
  
  
  import hashlib
  import json
  
  # Define the Block class
  class Block:
   def __init__(self, index, timestamp, data, previous_hash):
    self.index = index
    self.timestamp = timestamp
    self.data = data
    self.previous_hash = previous_hash
    self.hash = self.hash_block()
  
   # Create the hash of the block contents
   def hash_block(self):
    sha = hashlib.sha256()
    sha.update((str(self.index) + 
      str(self.timestamp) + 
      str(self.data) + 
      str(self.previous_hash)).encode('utf-8'))
    return sha.hexdigest()
  
  # Create the blockchain
  def create_blockchain():
    blockchain = [create_genesis_block()]
    previous_block = blockchain[0]
  
    # Add blocks for each item in the list of transactions
    for i in range(1, len(blockchain_transactions)):
      block_to_add = next_block(previous_block, blockchain_transactions[i])
      blockchain.append(block_to_add)
      previous_block = block_to_add
  
  # Print the blockchain
  def print_blockchain():
    for block in blockchain:
      block_index = str(block.index)
      block_timestamp = str(block.timestamp)
      block_data = str(block.data)
      block_hash = block.hash
      print(f"Block Index: {block_index}, Timestamp: {block_timestamp}, Data: {block_data}, Hash: {block_hash}")
  
  
  assert create_blockchain() == None
  assert print_blockchain() == None
output: def create_genesis_block():
      return Block(0, "01/01/2023", "Genesis Block", "0")
  
  def next_block(last_block, data):
      this_index = last_block.index + 1
      this_timestamp = "01/01/2023"
      this_data = data
      this_hash = last_block.hash
      return Block(this_index, this_timestamp, this_data, this_hash)
  
  blockchain_transactions = ["Transaction1", "Transaction2", "Transaction3"]
  blockchain = []