Add newlines - PEP8 style (#173)

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')
+        raise KeyError('Key not found')

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):

solutions/system_design/web_crawler/web_crawler_snippets.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+
 class PagesDataStore(object):
 
     def __init__(self, db):