input: 
  from typing import List
  
  def create_blockchain(blockchain_transactions: List[str]) -> List[Block]:
      """
      Create a simple blockchain system in Python, consisting of multiple blocks.
      Each block contains an index, timestamp, data, and the hash of the previous block.
      The blockchain starts with a genesis block and subsequent blocks are added based on the provided transactions.
      The function returns the complete blockchain as a list of Block instances.
      
      Example:
      >>> blockchain_transactions = ["Transaction 1", "Transaction 2"]
      >>> create_blockchain(blockchain_transactions)
      [
          <__main__.Block object at 0x7f9b8c0b4e80>,  # Genesis Block
          <__main__.Block object at 0x7f9b8c0b4f70>,  # Block for "Transaction 1"
          <__main__.Block object at 0x7f9b8c0b4f40>   # Block for "Transaction 2"
      ]
      """
  
output:     
      from hashlib import sha256
      from time import time
  
      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.calculate_hash()
  
          def calculate_hash(self):
              block_string = f"{self.index}{self.timestamp}{self.data}{self.previous_hash}"
              return sha256(block_string.encode()).hexdigest()
  
      blockchain = []
      genesis_block = Block(0, time(), "Genesis Block", "0")
      blockchain.append(genesis_block)
  
      for i, transaction in enumerate(blockchain_transactions, start=1):
          new_block = Block(i, time(), transaction, blockchain[-1].hash)
          blockchain.append(new_block)
  
      return blockchain
  