input: Write a function to create a simple blockchain system in Python. The function should generate a list of blocks, with each block containing an index, timestamp, data, and previous hash. The function should also include methods to generate the hash of the block and 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
output: 
  def create_blockchain():
   blockchain = [create_genesis_block()]
   previous_block = blockchain[0]
  
   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
  
  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
  