fix code layout

Author: yixu.cui

tracker/track_demo.py

@@ -327,4 +327,4 @@ def get_color(idx):
     if not os.path.exists(SAVE_FOLDER):  # demo save to a particular folder
         os.makedirs(SAVE_FOLDER)
         os.makedirs(os.path.join(SAVE_FOLDER, 'result_images'))
-    main(opts)
+    main(opts)