input: from typing import List
  
  
  def create_blockchain() -> List[Block]:
      """ Create a simple blockchain system in Python. The blockchain starts with a genesis block
      and then adds subsequent blocks for each transaction in the list of transactions.
      >>> create_blockchain()
      [Block(index=0, timestamp=1634567890, data="Genesis Block", previous_hash="0"),
       Block(index=1, timestamp=1634567895, data="Transaction Data 1", previous_hash=<hash of genesis block>),
       Block(index=2, timestamp=1634567900, data="Transaction Data 2", previous_hash=<hash of block 1>)]
      """
      
      # Define the Block class and other necessary functions here
      pass
output:     
      class Block:
          def __init__(self, index: int, timestamp: int, data: str, previous_hash: str):
              self.index = index
              self.timestamp = timestamp
              self.data = data
              self.previous_hash = previous_hash
              self.hash = self.calculate_hash()
          
          def calculate_hash(self) -> str:
              block_string = f"{self.index}{self.timestamp}{self.data}{self.previous_hash}"
              return hashlib.sha256(block_string.encode()).hexdigest()
      
      def create_blockchain() -> List[Block]:
          blockchain = []
          genesis_block = Block(index=0, timestamp=1634567890, data="Genesis Block", previous_hash="0")
          blockchain.append(genesis_block)
          
          transactions = ["Transaction Data 1", "Transaction Data 2"]
          previous_block = genesis_block
          
          for i, transaction in enumerate(transactions, start=1):
              new_block = Block(index=i, timestamp=1634567890 + i*5, data=transaction, previous_hash=previous_block.hash)
              blockchain.append(new_block)
              previous_block = new_block
          
          return blockchain
  