Typo fix
diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst
index 527032d..ed9ebb8 100644
--- a/Doc/library/contextlib.rst
+++ b/Doc/library/contextlib.rst
@@ -308,7 +308,7 @@
In the specific case of a single optional context manager, :class:`ExitStack`
instances can be used as a "do nothing" context manager, allowing a context
-managers to easily be omitted without affecting the overall structure of
+manager to easily be omitted without affecting the overall structure of
the source code::
def debug_trace(details):