input: from typing import Any, Dict
  
  
  def create_block(index: int, timestamp: str, data: Any, previous_hash: str) -> Dict:
      """ Create a block dictionary with given index, timestamp, data, and previous_hash,
      using the sha256 hash function to compute the block's hash.
      >>> create_block(0, '2020-01-01 12:00:00', 'Genesis Block', None)
      {'index': 0, 'timestamp': '2020-01-01 12:00:00', 'data': 'Genesis Block', 'previous_hash': None, 'hash': '9d518307aca077c0d5cf6ae0eefb4d83bef7f58ce38bcad6a37c8363b64e5dec'}
      >>> create_block(1, '2020-01-01 12:10:00', {'sender': 'Alice', 'receiver': 'Bob', 'amount': 5}, '9d518307aca077c0d5cf6ae0eefb4d83bef7f58ce38bcad6a37c8363b64e5dec')
      {'index': 1, 'timestamp': '2020-01-01 12:10:00', 'data': {'sender': 'Alice', 'receiver': 'Bob', 'amount': 5}, 'previous_hash': '9d518307aca077c0d5cf6ae0eefb4d83bef7f58ce38bcad6a37c8363b64e5dec', 'hash': '5c82cac837ce1afaae99abeadb77fb2e9cd7d97891b7ae6fa0b5f4cb9d618d4c'}
      """
output:     import hashlib
  
      block = {
          'index': index,
          'timestamp': timestamp,
          'data': data,
          'previous_hash': previous_hash
      }
      block_string = str(block).encode()
      hash_object = hashlib.sha256(block_string)
      block['hash'] = hash_object.hexdigest()
      return block