input: from typing import List
  
  
  def blockchain_data(blockchain_transactions: List[str]) -> str:
      """Create a simple blockchain system in Python and return the hash of the last block.
      >>> blockchain_data(['transaction1', 'transaction2', 'transaction3'])
      '4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
      >>> blockchain_data(['item1', 'item2', 'item3', 'item4'])
      '4e72baa113dd21b1fc4171dab045c65bda8de9fbcaffbfcd2bfb5c27db17a319'
      """
      
      import hashlib
      import json
      from datetime import datetime
  
      # 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 genesis block
      def create_genesis_block():
          return Block(0, datetime.now(), "Genesis Block", "0")
  
      # Create the next block
      def next_block(last_block, data):
          this_index = last_block.index + 1
          this_timestamp = datetime.now()
          this_data = data
          this_hash = last_block.hash
          return Block(this_index, this_timestamp, this_data, this_hash)
  
      # Create the blockchain
      def create_blockchain(transactions):
          blockchain = [create_genesis_block()]
          previous_block = blockchain[0]
  
          # Add blocks for each item in the list of transactions
          for transaction in transactions:
              block_to_add = next_block(previous_block, transaction)
              blockchain.append(block_to_add)
              previous_block = block_to_add
  
          return blockchain
  
      # Create the blockchain with given transactions
      blockchain = create_blockchain(blockchain_transactions)
  
      # Return the hash of the last block
      last_block = blockchain[-1]
      return last_block.hash
output:     
      import hashlib
      import json
      from datetime import datetime
  
      # 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 genesis block
      def create_genesis_block():
          return Block(0, datetime.now(), "Genesis Block", "0")
  
      # Create the next block
      def next_block(last_block, data):
          this_index = last_block.index + 1
          this_timestamp = datetime.now()
          this_data = data
          this_hash = last_block.hash
          return Block(this_index, this_timestamp, this_data, this_hash)
  
      # Create the blockchain
      def create_blockchain(transactions):
          blockchain = [create_genesis_block()]
          previous_block = blockchain[0]
  
          # Add blocks for each item in the list of transactions
          for transaction in transactions:
              block_to_add = next_block(previous_block, transaction)
              blockchain.append(block_to_add)
              previous_block = block_to_add
  
          return blockchain
  
      # Create the blockchain with given transactions
      blockchain = create_blockchain(blockchain_transactions)
  
      # Return the hash of the last block
      last_block = blockchain[-1]
      return last_block.hash
  