There's no need to default file to sys.stdout -- print(file=None) already
selects sys.stdout.
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 6cff722..2fb1ea5 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -711,8 +711,6 @@
 
     def printdir(self, file=None):
         """Print a table of contents for the zip file."""
-        if file is None:
-            file = sys.stdout
         print("%-46s %19s %12s" % ("File Name", "Modified    ", "Size"),
               file=file)
         for zinfo in self.filelist: