diff --git a/solutions/object_oriented_design/hash_table/hash_map.py b/solutions/object_oriented_design/hash_table/hash_map.py
index beceb77..33d9a35 100644
--- a/solutions/object_oriented_design/hash_table/hash_map.py
+++ b/solutions/object_oriented_design/hash_table/hash_map.py
@@ -35,4 +35,4 @@ class HashTable(object):
             if item.key == key:
                 del self.table[hash_index][index]
                 return
-        raise KeyError('Key not found')
\ No newline at end of file
+        raise KeyError('Key not found')
diff --git a/solutions/system_design/query_cache/query_cache_snippets.py b/solutions/system_design/query_cache/query_cache_snippets.py
index 6ea3bac..19d3f5c 100644
--- a/solutions/system_design/query_cache/query_cache_snippets.py
+++ b/solutions/system_design/query_cache/query_cache_snippets.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+
 class QueryApi(object):
 
     def __init__(self, memory_cache, reverse_index_cluster):
diff --git a/solutions/system_design/web_crawler/web_crawler_snippets.py b/solutions/system_design/web_crawler/web_crawler_snippets.py
index 99d5a37..d84a253 100644
--- a/solutions/system_design/web_crawler/web_crawler_snippets.py
+++ b/solutions/system_design/web_crawler/web_crawler_snippets.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+
 class PagesDataStore(object):
 
     def __init__(self, db):