input: Write a function to build a simple blockchain system in Python. The function should include the definition of the Block class, a method to create the blockchain, and a method to print the blockchain.
  assert create_blockchain()==[create_genesis_block(), next_block(create_genesis_block(), blockchain_transactions[1]), next_block(next_block(create_genesis_block(), blockchain_transactions[1]), blockchain_transactions[2])]==True
  assert print_blockchain()==["block index: 0, timestamp: 0, data: genesis block, hash: hash1", "block index: 1, timestamp: 1, data: transaction1, hash: hash2", "block index: 2, timestamp: 2, data: transaction2, hash: hash3"]==True
output: 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):
          return f"hash{self.index + 1}"
  
  def create_genesis_block():
      return Block(0, 0, "genesis block", "0")
  
  def next_block(last_block, data):
      index = last_block.index + 1
      timestamp = last_block.timestamp + 1
      return Block(index, timestamp, data, last_block.hash)
  
  def create_blockchain():
      blockchain_transactions = ["transaction1", "transaction2"]
      blockchain = [create_genesis_block()]
      for i in range(len(blockchain_transactions)):
          blockchain.append(next_block(blockchain[-1], blockchain_transactions[i]))
      return blockchain
  
  def print_blockchain():
      blockchain = create_blockchain()
      return [f"block index: {block.index}, timestamp: {block.timestamp}, data: {block.data}, hash: {block.hash}" for block in blockchain]