input: from typing import List, Dict
  
  def create_blockchain(blocks: List[Dict]) -> str:
      """ This function takes a list of dictionaries, each representing a block of data,
      and constructs a blockchain from them. Each block includes an index, a timestamp, 
      and some data. The function returns the entire blockchain in JSON format.
      >>> create_blockchain([
      ...     {'timestamp': '2023-01-01 12:00:00', 'data': 'Genesis Block'},
      ...     {'timestamp': '2023-01-02 12:00:00', 'data': 'Transaction1'},
      ...     {'timestamp': '2023-01-03 12:00:00', 'data': 'Transaction2'}
      ... ])
      '[
        {
          \\"index\\": 0,
          \\"timestamp\\": \\"2023-01-01 12:00:00\\",
          \\"data\\": \\"Genesis Block\\",
          \\"previous_hash\\": null,
          \\"hash\\": \\"17107a1f5fcec3c6fda9a67f9...\\"
        },
        {
          \\"index\\": 1,
          \\"timestamp\\": \\"2023-01-02 12:00:00\\",
          \\"data\\": \\"Transaction1\\",
          \\"previous_hash\\": \\"17107a1f5fcec3c6fda9a67f9...\\",
          \\"hash\\": \\"a2f7c4e678d2a1b92b3b4c5...\\"
        },
        {
          \\"index\\": 2,
          \\"timestamp\\": \\"2023-01-03 12:00:00\\",
          \\"data\\": \\"Transaction2\\",
          \\"previous_hash\\": \\"a2f7c4e678d2a1b92b3b4c5...\\",
          \\"hash\\": \\"9b4e6a783c2d1b9e8f7c6a5...\\"
        }
      ]'
      """
output:     import json
      import hashlib
  
      def calculate_hash(index, timestamp, data, previous_hash):
          block_string = f"{index}{timestamp}{data}{previous_hash}"
          return hashlib.sha256(block_string.encode()).hexdigest()
  
      blockchain = []
      previous_hash = None
  
      for index, block in enumerate(blocks):
          block_hash = calculate_hash(index, block['timestamp'], block['data'], previous_hash)
          blockchain.append({
              "index": index,
              "timestamp": block['timestamp'],
              "data": block['data'],
              "previous_hash": previous_hash,
              "hash": block_hash
          })
          previous_hash = block_hash
  
      return json.dumps(blockchain, indent=2)