From b02379d7698fce23c34164e342310aaefc20e300 Mon Sep 17 00:00:00 2001
From: aw3717 <1042.aw@gmail.com>
Date: Sun, 15 Oct 2017 21:26:31 -0600
Subject: [PATCH] fixed type errors

---
 blockchain.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/blockchain.py b/blockchain.py
index f55b269..bc2568f 100644
--- a/blockchain.py
+++ b/blockchain.py
@@ -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: int, previous_hash: Optional[str]=None) -> Dict[str, Any]:
         """
         Create a new Block in the Blockchain
 
@@ -132,7 +132,7 @@ class Blockchain:
         return self.last_block['index'] + 1
 
     @property
-    def last_block(self) -> Dict[str: Any]:
+    def last_block(self) -> Dict[str, Any]:
         return self.chain[-1]
 
     @staticmethod