Fix minor markup typo (#5407)
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index e472257..bfb813c 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1423,7 +1423,7 @@
a regular function and do something with its result. This is needed
in some cases where you need a reference to a function from a class
body and you want to avoid the automatic transformation to instance
- method. For these cases, use this idiom:
+ method. For these cases, use this idiom::
class C:
builtin_open = staticmethod(open)