Issue #28496: Mark up constants 0, 1 and -1 that denote return values or
special input values as literal text.
diff --git a/Doc/c-api/set.rst b/Doc/c-api/set.rst
index 8de0394..64b6dde 100644
--- a/Doc/c-api/set.rst
+++ b/Doc/c-api/set.rst
@@ -114,7 +114,7 @@
 
 .. c:function:: int PySet_Contains(PyObject *anyset, PyObject *key)
 
-   Return 1 if found, 0 if not found, and -1 if an error is encountered.  Unlike
+   Return ``1`` if found, ``0`` if not found, and ``-1`` if an error is encountered.  Unlike
    the Python :meth:`__contains__` method, this function does not automatically
    convert unhashable sets into temporary frozensets.  Raise a :exc:`TypeError` if
    the *key* is unhashable. Raise :exc:`PyExc_SystemError` if *anyset* is not a
@@ -125,8 +125,8 @@
 
    Add *key* to a :class:`set` instance.  Also works with :class:`frozenset`
    instances (like :c:func:`PyTuple_SetItem` it can be used to fill-in the values
-   of brand new frozensets before they are exposed to other code).  Return 0 on
-   success or -1 on failure. Raise a :exc:`TypeError` if the *key* is
+   of brand new frozensets before they are exposed to other code).  Return ``0`` on
+   success or ``-1`` on failure. Raise a :exc:`TypeError` if the *key* is
    unhashable. Raise a :exc:`MemoryError` if there is no room to grow.  Raise a
    :exc:`SystemError` if *set* is not an instance of :class:`set` or its
    subtype.
@@ -138,7 +138,7 @@
 
 .. c:function:: int PySet_Discard(PyObject *set, PyObject *key)
 
-   Return 1 if found and removed, 0 if not found (no action taken), and -1 if an
+   Return ``1`` if found and removed, ``0`` if not found (no action taken), and ``-1`` if an
    error is encountered.  Does not raise :exc:`KeyError` for missing keys.  Raise a
    :exc:`TypeError` if the *key* is unhashable.  Unlike the Python :meth:`~set.discard`
    method, this function does not automatically convert unhashable sets into