Remove unused or redundant imports in concurrent.futures and multiprocessing.
diff --git a/Lib/multiprocessing/synchronize.py b/Lib/multiprocessing/synchronize.py
index 70ae825..e35bbff 100644
--- a/Lib/multiprocessing/synchronize.py
+++ b/Lib/multiprocessing/synchronize.py
@@ -37,14 +37,11 @@
     ]
 
 import threading
-import os
 import sys
 
-from time import time as _time, sleep as _sleep
-
 import _multiprocessing
 from multiprocessing.process import current_process
-from multiprocessing.util import Finalize, register_after_fork, debug
+from multiprocessing.util import register_after_fork, debug
 from multiprocessing.forking import assert_spawning, Popen
 
 # Try to import the mp.synchronize module cleanly, if it fails