Remove Type Annotations

I have some reasons for this, but could be swayed to keep them:

- For folks who are learning, it tends to get in the way—there are way
too many questions about this.
- It doesn’t bring much value if there are reasonable tests.
- Not many folks are using `mypy` before run time.

blockchain.py

@@ -18,7 +18,7 @@ class Blockchain:
         # Create the genesis block
         self.new_block(previous_hash='1', proof=100)
 
-    def register_node(self, address: str) -> None:
+    def register_node(self, address):
         """
         Add a new node to the list of nodes
 
@@ -28,7 +28,7 @@ class Blockchain:
         parsed_url = urlparse(address)
         self.nodes.add(parsed_url.netloc)
 
-    def valid_chain(self, chain: List[Dict[str, Any]]) -> bool:
+    def valid_chain(self, chain):
         """
         Determine if a given blockchain is valid
 
@@ -57,7 +57,7 @@ class Blockchain:
 
         return True
 
-    def resolve_conflicts(self) -> bool:
+    def resolve_conflicts(self):
         """
         This is our consensus algorithm, it resolves conflicts
         by replacing our chain with the longest one in the network.
@@ -91,7 +91,7 @@ class Blockchain:
 
         return False
 
-    def new_block(self, proof: int, previous_hash: Optional[str]) -> Dict[str, Any]:
+    def new_block(self, proof, previous_hash):
         """
         Create a new Block in the Blockchain
 
@@ -114,7 +114,7 @@ class Blockchain:
         self.chain.append(block)
         return block
 
-    def new_transaction(self, sender: str, recipient: str, amount: int) -> int:
+    def new_transaction(self, sender, recipient, amount):
         """
         Creates a new transaction to go into the next mined Block
 
@@ -132,11 +132,11 @@ class Blockchain:
         return self.last_block['index'] + 1
 
     @property
-    def last_block(self) -> Dict[str, Any]:
+    def last_block(self):
         return self.chain[-1]
 
     @staticmethod
-    def hash(block: Dict[str, Any]) -> str:
+    def hash(block):
         """
         Creates a SHA-256 hash of a Block
 
@@ -147,7 +147,7 @@ class Blockchain:
         block_string = json.dumps(block, sort_keys=True).encode()
         return hashlib.sha256(block_string).hexdigest()
 
-    def proof_of_work(self, last_proof: int) -> int:
+    def proof_of_work(self, last_proof):
         """
         Simple Proof of Work Algorithm:
          - Find a number p' such that hash(pp') contains leading 4 zeroes, where p is the previous p'
@@ -161,7 +161,7 @@ class Blockchain:
         return proof
 
     @staticmethod
-    def valid_proof(last_proof: int, proof: int) -> bool:
+    def valid_proof(last_proof, proof):
         """
         Validates the Proof