diff --git a/blockchain/pow_algorithm.py b/blockchain/pow_algorithm.py
index 65e2f59b6..cd4213e92 100644
--- a/blockchain/pow_algorithm.py
+++ b/blockchain/pow_algorithm.py
@@ -9,6 +9,7 @@
 import hashlib
 import time
 
+
 class Block:
     def __init__(
         self,
@@ -16,7 +17,7 @@ class Block:
         previous_hash: str,
         transactions: str,
         timestamp: float,
-        difficulty: int
+        difficulty: int,
     ) -> None:
         """
         Initializes a Block object with the specified parameters.
@@ -42,7 +43,7 @@ class Block:
         Generates the hash of the block content.
         Combines index, previous hash, transactions, timestamp, and nonce into
         a string, which is then hashed using SHA-256.
-        
+
         Returns:
         - str: The hash of the block.
         """
@@ -57,17 +58,20 @@ class Block:
         Performs Proof of Work by adjusting the nonce until a valid hash is found.
         A valid hash has the required number of leading zeros based on the
         difficulty level.
-        
+
         Returns:
         - None
         """
-        target = '0' * self.difficulty  # Target hash should start with 'difficulty' zeros
-        while self.hash[:self.difficulty] != target:
+        target = (
+            "0" * self.difficulty
+        )  # Target hash should start with 'difficulty' zeros
+        while self.hash[: self.difficulty] != target:
             self.nonce += 1
             self.hash = self.compute_hash()
 
         print(f"Block mined with nonce {self.nonce}, hash: {self.hash}")
 
+
 class Blockchain:
     def __init__(self, difficulty: int) -> None:
         """
@@ -75,7 +79,7 @@ class Blockchain:
 
         Parameters:
         - difficulty (int): The difficulty level for mining blocks in this blockchain.
-        
+
         Returns:
         - None
         """
@@ -86,7 +90,7 @@ class Blockchain:
     def create_genesis_block(self) -> None:
         """
         Creates the first block in the blockchain (the Genesis block).
-        
+
         Returns:
         - None
         """
@@ -100,21 +104,24 @@ class Blockchain:
 
         Parameters:
         - transactions (str): The list of transactions to be added in the new block.
-        
+
         Returns:
         - None
         """
         previous_block = self.chain[-1]
         new_block = Block(
-            len(self.chain), previous_block.hash, transactions, time.time(), 
-            self.difficulty
+            len(self.chain),
+            previous_block.hash,
+            transactions,
+            time.time(),
+            self.difficulty,
         )
         new_block.mine_block()
         self.chain.append(new_block)
 
     def is_chain_valid(self) -> bool:
         """
-        Verifies the integrity of the blockchain by ensuring each block's previous 
+        Verifies the integrity of the blockchain by ensuring each block's previous
         hash matches and that all blocks meet the Proof of Work requirement.
 
         Returns:
@@ -134,15 +141,17 @@ class Blockchain:
 
         return True
 
+
 # Test cases
 
+
 ## Test Case 1: Blockchain Initialization and Genesis Block
 # This test verifies if the blockchain is correctly initialized with a Genesis block
 # and if the block is successfully mined.
 def test_blockchain() -> None:
     """
     Test cases for the Blockchain proof of work algorithm.
-    
+
     Returns:
     - None
     """
@@ -162,14 +171,19 @@ def test_blockchain() -> None:
     ## Test Case 4: Tampering with the blockchain
     # This test simulates tampering with the blockchain and checks that the validation
     # correctly detects the tampering.
-    blockchain.chain[1].transactions = "Transaction 1: Alice pays Bob 50 BTC"  # Tampering
-    assert not blockchain.is_chain_valid(), "Blockchain should be invalid due to tampering"
+    blockchain.chain[
+        1
+    ].transactions = "Transaction 1: Alice pays Bob 50 BTC"  # Tampering
+    assert (
+        not blockchain.is_chain_valid()
+    ), "Blockchain should be invalid due to tampering"
 
     ## Test Case 5: Correct blockchain validation
     # This test checks if the blockchain becomes invalid after tampering and verifies
     # if the PoW still holds after tampering is done.
-    
+
     print("All test cases passed.")
 
+
 if __name__ == "__main__":
     test_blockchain()