input: 
  from typing import List, Any
  import hashlib
  import json
  
  def create_blockchain(data_entries: List[Any]) -> str:
      """ Create a basic blockchain system in Python and return the entire blockchain
      in JSON format after adding the provided data entries.
      Each entry is expected to have a 'timestamp' and 'data' field.
      >>> create_blockchain([{'timestamp': '2023-01-01T00:00:00', 'data': 'Genesis Block'}, {'timestamp': '2023-01-02T00:00:00', 'data': 'Block 1 Data'}])
      '[
        {
          "index": 0,
          "timestamp": "2023-01-01T00:00:00",
          "data": "Genesis Block",
          "previous_hash": null,
          "hash": "4a55ec74ba2e00ff6a011aa33f66453ee84bedae97b9cf2e392ed0adad749c9a"
        },
        {
          "index": 1,
          "timestamp": "2023-01-02T00:00:00",
          "data": "Block 1 Data",
          "previous_hash": "4a55ec74ba2e00ff6a011aa33f66453ee84bedae97b9cf2e392ed0adad749c9a",
          "hash": "8c13ee9c131e43228a9934fa19f40b699bc6908efe3be22152a66cf49ea8f68a"
        }
      ]'
      """
      # We will use SHA256 as our hashing function
      def sha256(data: str) -> str:
          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: int, timestamp: str, data: Any, previous_hash: str):
              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: Any):
              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) -> str:
              return json.dumps([b.__dict__ for b in self.chain], indent=2)
  
      bc = Blockchain()
      for entry in data_entries:
          bc.add_block(entry)
      return bc.get_chain()
  
output:     bc = Blockchain()
      for entry in data_entries:
          bc.add_block(entry)
      return bc.get_chain()