#9237: document sys.call_tracing().
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 6540311..23fdb09 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -55,6 +55,13 @@
``modules.keys()`` only lists the imported modules.)
+.. function:: call_tracing(func, args)
+
+ Call ``func(*args)``, while tracing is enabled. The tracing state is saved,
+ and restored afterwards. This is intended to be called from a debugger from
+ a checkpoint, to recursively debug some other code.
+
+
.. data:: copyright
A string containing the copyright pertaining to the Python interpreter.