input: Write a function to build a simple blockchain system in Python. The function should include a Block class, a hash function for the block, a function to create the blockchain, and a function to print the blockchain. Return the blockchain as a list of blocks.
  
  assert build_simple_blockchain() == [create_genesis_block(), next_block(blockchain[0], blockchain_transactions[1]), next_block(blockchain[1], blockchain_transactions[2]), ...]
output: def build_simple_blockchain():
      import hashlib
      import time
  
      class Block:
          def __init__(self, index, previous_hash, timestamp, data, hash):
              self.index = index
              self.previous_hash = previous_hash
              self.timestamp = timestamp
              self.data = data
              self.hash = hash
  
      def calculate_hash(index, previous_hash, timestamp, data):
          value = str(index) + str(previous_hash) + str(timestamp) + str(data)
          return hashlib.sha256(value.encode('utf-8')).hexdigest()
  
      def create_genesis_block():
          return Block(0, "0", int(time.time()), "Genesis Block", calculate_hash(0, "0", int(time.time()), "Genesis Block"))
  
      def next_block(last_block, data):
          this_index = last_block.index + 1
          this_timestamp = int(time.time())
          this_hash = calculate_hash(this_index, last_block.hash, this_timestamp, data)
          return Block(this_index, last_block.hash, this_timestamp, data, this_hash)
  
      blockchain = [create_genesis_block()]
      blockchain_transactions = ["Transaction1", "Transaction2", "Transaction3"]
  
      for i in range(1, len(blockchain_transactions)):
          blockchain.append(next_block(blockchain[-1], blockchain_transactions[i]))
  
      return blockchain