input: Write a function to implement 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. Provide assert statements to verify the correctness of the implementation. If the input is not applicable, return a blockchain with a single genesis block.
  assert create_blockchain() == [<Block object representing the genesis block>]
  assert print_blockchain() == None  # No output assertion for print methods
output: def create_blockchain():
      class Block:
          def __init__(self, index, previous_hash, data, hash):
              self.index = index
              self.previous_hash = previous_hash
              self.data = data
              self.hash = hash
  
      genesis_block = Block(0, "0", "Genesis Block", "genesis_hash")
      blockchain = [genesis_block]
      return blockchain
  
  def print_blockchain(blockchain):
      for block in blockchain:
          print(f"Index: {block.index}, Previous Hash: {block.previous_hash}, Data: {block.data}, Hash: {block.hash}")