Fix a circular import dependency.
diff --git a/Lib/weakref.py b/Lib/weakref.py
index 5f672c6..6663c26 100644
--- a/Lib/weakref.py
+++ b/Lib/weakref.py
@@ -9,8 +9,6 @@
 # they are called this instead of "ref" to avoid name collisions with
 # the module-global ref() function imported from _weakref.
 
-import collections
-
 from _weakref import (
      getweakrefcount,
      getweakrefs,
@@ -22,6 +20,8 @@
 
 from _weakrefset import WeakSet
 
+import collections  # Import after _weakref to avoid circular import.
+
 ProxyTypes = (ProxyType, CallableProxyType)
 
 __all__ = ["ref", "proxy", "getweakrefcount", "getweakrefs",