Add cross-references to the glossary entry for file objects.
diff --git a/Doc/tutorial/inputoutput.rst b/Doc/tutorial/inputoutput.rst
index dbb56f6..84e83b5 100644
--- a/Doc/tutorial/inputoutput.rst
+++ b/Doc/tutorial/inputoutput.rst
@@ -232,8 +232,8 @@
builtin: open
object: file
-:func:`open` returns a file object, and is most commonly used with two
-arguments: ``open(filename, mode)``.
+:func:`open` returns a :term:`file object`, and is most commonly used with
+two arguments: ``open(filename, mode)``.
::