add example function
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 0d92170..ddd7e64 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -784,7 +784,13 @@
The standard streams are in text mode by default. To write or read binary
data to these, use the underlying binary buffer. For example, to write bytes
to :data:`stdout`, use ``sys.stdout.buffer.write(b'abc')``. Using
- :meth:`io.TextIOWrapper.detach` streams can be made binary by default.
+ :meth:`io.TextIOWrapper.detach` streams can be made binary by default. For
+ example, this function sets all the standard streams to binary: ::
+
+ def make_streams_binary():
+ sys.stdin = sys.stdin.detach()
+ sys.stdout = sys.stout.detach()
+ sys.stderr = sys.stderr.detach()
.. data:: __stdin__