input: def basic_blockchain():
      """Compose a basic blockchain system in Python.
      >>> bc = Blockchain()
      >>> bc.add_block({'timestamp': '2023-01-01 12:00:00', 'data': 'Genesis Block'})
      >>> bc.add_block({'timestamp': '2023-01-02 12:00:00', 'data': 'Block 1'})
      >>> bc.get_chain()
      '[{"index": 0, "timestamp": "2023-01-01 12:00:00", "data": "Genesis Block", "previous_hash": null, "hash": "..."}, {"index": 1, "timestamp": "2023-01-02 12:00:00", "data": "Block 1", "previous_hash": "...", "hash": "..."}]'
      """
      import hashlib
      import json
  
      # We will use SHA256 as our hashing function
      def sha256(data):
          hash_function = hashlib.sha256()
          hash_function.update(data.encode('utf-8'))
          return hash_function.hexdigest()
  
      # Create a class for each block
      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 = sha256(f'{self.index}{self.timestamp}{self.data}{self.previous_hash}')
  
      # Create a class for the blockchain
      class Blockchain:
          def __init__(self):
              self.chain = []
  
          def add_block(self, data):
              previous_hash = self.chain[-1].hash if len(self.chain) > 0 else None
              block = Block(len(self.chain), data['timestamp'], data['data'], previous_hash)
              self.chain.append(block)
  
          # This method will return the entire blockchain in JSON format
          def get_chain(self):
              return json.dumps([b.__dict__ for b in self.chain], indent=2)
output:     # Create a genesis block if the blockchain is empty
      def create_genesis_block(self):
          if len(self.chain) == 0:
              genesis_block = Block(0, '2023-01-01 12:00:00', 'Genesis Block', None)
              self.chain.append(genesis_block)
  
      # Initialize the blockchain with a genesis block
      def __init__(self):
          self.chain = []
          self.create_genesis_block()