Remove duplication.
diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index 5f1b9bf..1f1d775 100644
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -864,7 +864,7 @@
Pass the barrier. When all the threads party to the barrier have called
this function, they are all released simultaneously. If a *timeout* is
- provided, is is used in preference to any that was supplied to the class
+ provided, it is used in preference to any that was supplied to the class
constructor.
The return value is an integer in the range 0 to *parties* -- 1, different