Remove (object) from class declarations. (#6658)

streaming/python/examples/key_selectors.py

@@ -17,7 +17,7 @@ parser.add_argument("--input-file", required=True, help="the input text file")
 
 
 # A class used to check attribute-based key selection
-class Record(object):
+class Record:
     def __init__(self, record):
         k, _ = record
         self.word = k

streaming/python/examples/wordcount.py

@@ -23,7 +23,7 @@ parser.add_argument(
 # A custom data source that reads articles from wikipedia
 # Custom data sources need to implement a get_next() method
 # that returns the next data element, in this case sentences
-class Wikipedia(object):
+class Wikipedia:
     def __init__(self, title_file):
         # Titles in this file will be as queries
         self.title_file = title_file