import hashlib

class Block:
def init(self, data, previous_hash):
self.data = data
self.previous_hash = previous_hash
self.hash = self.calculate_hash()

def calculate_hash(self):
    hash_digest = hashlib.sha256()
    hash_digest.update(str(self.data).encode('utf-8'))
    hash_digest.update(str(self.previous_hash).encode('utf-8'))
    return hash_digest.hexdigest()

def create_genesis_block():
return Block('Genesis block', '0')

def next_block(previous_block):
return Block('Block 2', previous_block.hash)

genesis_block = create_genesis_block()
block_1 = next_block(genesis_block)
block_2 = next_block(block_1)

print(genesis_block.hash)
print(block_1.hash)
print(block_2.hash)