input: 
  def create_basic_blockchain():
      """ Create a basic blockchain in Python using only the core modules.
      The blockchain class should support creating blocks, recording transactions,
      and hashing blocks using the SHA-256 algorithm.
      
      >>> blockchain = create_basic_blockchain()
      >>> block = blockchain.create_block(0, '0')
      >>> assert len(blockchain.chain) == 1
      >>> assert blockchain.hash_block(block).startswith('0')
      """
  
output:     
      class Block:
          def __init__(self, index, previous_hash, transactions):
              self.index = index
              self.previous_hash = previous_hash
              self.transactions = transactions
              self.timestamp = time.time()
              self.nonce = 0
  
          def compute_hash(self):
              block_string = json.dumps(self.__dict__, sort_keys=True).encode()
              return hashlib.sha256(block_string).hexdigest()
  
      class Blockchain:
          def __init__(self):
              self.chain = []
              self.create_genesis_block()
  
          def create_genesis_block(self):
              genesis_block = Block(0, "0", [])
              self.chain.append(genesis_block)
  
          def create_block(self, previous_index, previous_hash):
              block = Block(previous_index + 1, previous_hash, [])
              self.chain.append(block)
              return block
  
          def hash_block(self, block):
              return block.compute_hash()
  
      return Blockchain()
  