diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index c7ae60281c2f58..00e228bca4375b 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -419,8 +419,13 @@ buffered_dealloc(buffered *self)
     Py_DECREF(tp);
 }
 
+/*[clinic input]
+_io._Buffered.__sizeof__
+[clinic start generated code]*/
+
 static PyObject *
-buffered_sizeof(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered___sizeof___impl(buffered *self)
+/*[clinic end generated code: output=0231ef7f5053134e input=753c782d808d34df]*/
 {
     size_t res = _PyObject_SIZE(Py_TYPE(self));
     if (self->buffer) {
@@ -450,8 +455,17 @@ buffered_clear(buffered *self)
 /* Because this can call arbitrary code, it shouldn't be called when
    the refcount is 0 (that is, not directly from tp_dealloc unless
    the refcount has been temporarily re-incremented). */
+/*[clinic input]
+_io._Buffered._dealloc_warn
+
+    source: object
+    /
+
+[clinic start generated code]*/
+
 static PyObject *
-buffered_dealloc_warn(buffered *self, PyObject *source)
+_io__Buffered__dealloc_warn(buffered *self, PyObject *source)
+/*[clinic end generated code: output=690dcc3df8967162 input=8f845f2a4786391c]*/
 {
     if (self->ok && self->raw) {
         PyObject *r;
@@ -471,9 +485,13 @@ buffered_dealloc_warn(buffered *self, PyObject *source)
  */
 
 /* Flush and close */
+/*[clinic input]
+_io._Buffered.flush as _io__Buffered_simple_flush
+[clinic start generated code]*/
 
 static PyObject *
-buffered_simple_flush(buffered *self, PyObject *args)
+_io__Buffered_simple_flush_impl(buffered *self)
+/*[clinic end generated code: output=29ebb3820db1bdfd input=f33ef045e7250767]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(flush));
@@ -500,8 +518,13 @@ buffered_closed_get(buffered *self, void *context)
     return PyObject_GetAttr(self->raw, &_Py_ID(closed));
 }
 
+/*[clinic input]
+_io._Buffered.close
+[clinic start generated code]*/
+
 static PyObject *
-buffered_close(buffered *self, PyObject *args)
+_io__Buffered_close_impl(buffered *self)
+/*[clinic end generated code: output=7280b7b42033be0c input=d20b83d1ddd7d805]*/
 {
     PyObject *res = NULL;
     int r;
@@ -520,7 +543,7 @@ buffered_close(buffered *self, PyObject *args)
     }
 
     if (self->finalizing) {
-        PyObject *r = buffered_dealloc_warn(self, (PyObject *) self);
+        PyObject *r = _io__Buffered__dealloc_warn(self, (PyObject *) self);
         if (r)
             Py_DECREF(r);
         else
@@ -560,10 +583,13 @@ buffered_close(buffered *self, PyObject *args)
     return res;
 }
 
-/* detach */
+/*[clinic input]
+_io._Buffered.detach
+[clinic start generated code]*/
 
 static PyObject *
-buffered_detach(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_detach_impl(buffered *self)
+/*[clinic end generated code: output=dd0fc057b8b779f7 input=482762a345cc9f44]*/
 {
     PyObject *raw, *res;
     CHECK_INITIALIZED(self)
@@ -580,22 +606,37 @@ buffered_detach(buffered *self, PyObject *Py_UNUSED(ignored))
 
 /* Inquiries */
 
+/*[clinic input]
+_io._Buffered.seekable
+[clinic start generated code]*/
+
 static PyObject *
-buffered_seekable(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_seekable_impl(buffered *self)
+/*[clinic end generated code: output=90172abb5ceb6e8f input=7d35764f5fb5262b]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(seekable));
 }
 
+/*[clinic input]
+_io._Buffered.readable
+[clinic start generated code]*/
+
 static PyObject *
-buffered_readable(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_readable_impl(buffered *self)
+/*[clinic end generated code: output=92afa07661ecb698 input=640619addb513b8b]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(readable));
 }
 
+/*[clinic input]
+_io._Buffered.writable
+[clinic start generated code]*/
+
 static PyObject *
-buffered_writable(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_writable_impl(buffered *self)
+/*[clinic end generated code: output=4e3eee8d6f9d8552 input=b35ea396b2201554]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(writable));
@@ -617,15 +658,25 @@ buffered_mode_get(buffered *self, void *context)
 
 /* Lower-level APIs */
 
+/*[clinic input]
+_io._Buffered.fileno
+[clinic start generated code]*/
+
 static PyObject *
-buffered_fileno(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_fileno_impl(buffered *self)
+/*[clinic end generated code: output=b717648d58a95ee3 input=768ea30b3f6314a7]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(fileno));
 }
 
+/*[clinic input]
+_io._Buffered.isatty
+[clinic start generated code]*/
+
 static PyObject *
-buffered_isatty(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_isatty_impl(buffered *self)
+/*[clinic end generated code: output=c20e55caae67baea input=9ea007b11559bee4]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(isatty));
@@ -830,8 +881,13 @@ buffered_flush_and_rewind_unlocked(buffered *self)
     Py_RETURN_NONE;
 }
 
+/*[clinic input]
+_io._Buffered.flush
+[clinic start generated code]*/
+
 static PyObject *
-buffered_flush(buffered *self, PyObject *args)
+_io__Buffered_flush_impl(buffered *self)
+/*[clinic end generated code: output=da2674ef1ce71f3a input=fda63444697c6bf4]*/
 {
     PyObject *res;
 
@@ -1205,8 +1261,13 @@ _io__Buffered_readline_impl(buffered *self, Py_ssize_t size)
 }
 
 
+/*[clinic input]
+_io._Buffered.tell
+[clinic start generated code]*/
+
 static PyObject *
-buffered_tell(buffered *self, PyObject *Py_UNUSED(ignored))
+_io__Buffered_tell_impl(buffered *self)
+/*[clinic end generated code: output=386972ae84716c1e input=ad61e04a6b349573]*/
 {
     Py_off_t pos;
 
@@ -1318,20 +1379,21 @@ _io__Buffered_seek_impl(buffered *self, PyObject *targetobj, int whence)
 
 /*[clinic input]
 _io._Buffered.truncate
+    cls: defining_class
     pos: object = None
     /
 [clinic start generated code]*/
 
 static PyObject *
-_io__Buffered_truncate_impl(buffered *self, PyObject *pos)
-/*[clinic end generated code: output=667ca03c60c270de input=8a1be34d57cca2d3]*/
+_io__Buffered_truncate_impl(buffered *self, PyTypeObject *cls, PyObject *pos)
+/*[clinic end generated code: output=fe3882fbffe79f1a input=f5b737d97d76303f]*/
 {
     PyObject *res = NULL;
 
     CHECK_INITIALIZED(self)
     CHECK_CLOSED(self, "truncate of closed file")
     if (!self->writable) {
-        _PyIO_State *state = IO_STATE();
+        _PyIO_State *state = get_io_state_by_cls(cls);
         return bufferediobase_unsupported(state, "truncate");
     }
     if (!ENTER_BUFFERED(self))
@@ -2427,14 +2489,14 @@ PyTypeObject PyBufferedIOBase_Type = {
 
 static PyMethodDef bufferedreader_methods[] = {
     /* BufferedIOMixin methods */
-    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
-    {"flush", (PyCFunction)buffered_simple_flush, METH_NOARGS},
-    {"close", (PyCFunction)buffered_close, METH_NOARGS},
-    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
-    {"readable", (PyCFunction)buffered_readable, METH_NOARGS},
-    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
-    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
-    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SIMPLE_FLUSH_METHODDEF
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_READABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
 
     _IO__BUFFERED_READ_METHODDEF
     _IO__BUFFERED_PEEK_METHODDEF
@@ -2443,9 +2505,9 @@ static PyMethodDef bufferedreader_methods[] = {
     _IO__BUFFERED_READINTO1_METHODDEF
     _IO__BUFFERED_READLINE_METHODDEF
     _IO__BUFFERED_SEEK_METHODDEF
-    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
+    _IO__BUFFERED_TELL_METHODDEF
     _IO__BUFFERED_TRUNCATE_METHODDEF
-    {"__sizeof__", (PyCFunction)buffered_sizeof, METH_NOARGS},
+    _IO__BUFFERED___SIZEOF___METHODDEF
     {NULL, NULL}
 };
 
@@ -2489,20 +2551,20 @@ PyType_Spec bufferedreader_spec = {
 
 static PyMethodDef bufferedwriter_methods[] = {
     /* BufferedIOMixin methods */
-    {"close", (PyCFunction)buffered_close, METH_NOARGS},
-    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
-    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
-    {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
-    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
-    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
-    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_WRITABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
 
     _IO_BUFFEREDWRITER_WRITE_METHODDEF
     _IO__BUFFERED_TRUNCATE_METHODDEF
-    {"flush", (PyCFunction)buffered_flush, METH_NOARGS},
+    _IO__BUFFERED_FLUSH_METHODDEF
     _IO__BUFFERED_SEEK_METHODDEF
-    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
-    {"__sizeof__", (PyCFunction)buffered_sizeof, METH_NOARGS},
+    _IO__BUFFERED_TELL_METHODDEF
+    _IO__BUFFERED___SIZEOF___METHODDEF
     {NULL, NULL}
 };
 
@@ -2596,19 +2658,19 @@ PyType_Spec bufferedrwpair_spec = {
 
 static PyMethodDef bufferedrandom_methods[] = {
     /* BufferedIOMixin methods */
-    {"close", (PyCFunction)buffered_close, METH_NOARGS},
-    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
-    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
-    {"readable", (PyCFunction)buffered_readable, METH_NOARGS},
-    {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
-    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
-    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
-    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_READABLE_METHODDEF
+    _IO__BUFFERED_WRITABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
 
-    {"flush", (PyCFunction)buffered_flush, METH_NOARGS},
+    _IO__BUFFERED_FLUSH_METHODDEF
 
     _IO__BUFFERED_SEEK_METHODDEF
-    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
+    _IO__BUFFERED_TELL_METHODDEF
     _IO__BUFFERED_TRUNCATE_METHODDEF
     _IO__BUFFERED_READ_METHODDEF
     _IO__BUFFERED_READ1_METHODDEF
@@ -2617,7 +2679,7 @@ static PyMethodDef bufferedrandom_methods[] = {
     _IO__BUFFERED_READLINE_METHODDEF
     _IO__BUFFERED_PEEK_METHODDEF
     _IO_BUFFEREDWRITER_WRITE_METHODDEF
-    {"__sizeof__", (PyCFunction)buffered_sizeof, METH_NOARGS},
+    _IO__BUFFERED___SIZEOF___METHODDEF
     {NULL, NULL}
 };
 
diff --git a/Modules/_io/clinic/bufferedio.c.h b/Modules/_io/clinic/bufferedio.c.h
index a898b01899babe..e2ac90c54a10f0 100644
--- a/Modules/_io/clinic/bufferedio.c.h
+++ b/Modules/_io/clinic/bufferedio.c.h
@@ -266,6 +266,184 @@ _io__BufferedIOBase_write(PyObject *self, PyTypeObject *cls, PyObject *const *ar
     return return_value;
 }
 
+PyDoc_STRVAR(_io__Buffered___sizeof____doc__,
+"__sizeof__($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED___SIZEOF___METHODDEF    \
+    {"__sizeof__", (PyCFunction)_io__Buffered___sizeof__, METH_NOARGS, _io__Buffered___sizeof____doc__},
+
+static PyObject *
+_io__Buffered___sizeof___impl(buffered *self);
+
+static PyObject *
+_io__Buffered___sizeof__(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered___sizeof___impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered__dealloc_warn__doc__,
+"_dealloc_warn($self, source, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED__DEALLOC_WARN_METHODDEF    \
+    {"_dealloc_warn", (PyCFunction)_io__Buffered__dealloc_warn, METH_O, _io__Buffered__dealloc_warn__doc__},
+
+PyDoc_STRVAR(_io__Buffered_simple_flush__doc__,
+"flush($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_SIMPLE_FLUSH_METHODDEF    \
+    {"flush", (PyCFunction)_io__Buffered_simple_flush, METH_NOARGS, _io__Buffered_simple_flush__doc__},
+
+static PyObject *
+_io__Buffered_simple_flush_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_simple_flush(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_simple_flush_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_close__doc__,
+"close($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_CLOSE_METHODDEF    \
+    {"close", (PyCFunction)_io__Buffered_close, METH_NOARGS, _io__Buffered_close__doc__},
+
+static PyObject *
+_io__Buffered_close_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_close(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_close_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_detach__doc__,
+"detach($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_DETACH_METHODDEF    \
+    {"detach", (PyCFunction)_io__Buffered_detach, METH_NOARGS, _io__Buffered_detach__doc__},
+
+static PyObject *
+_io__Buffered_detach_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_detach(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_detach_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_seekable__doc__,
+"seekable($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_SEEKABLE_METHODDEF    \
+    {"seekable", (PyCFunction)_io__Buffered_seekable, METH_NOARGS, _io__Buffered_seekable__doc__},
+
+static PyObject *
+_io__Buffered_seekable_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_seekable(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_seekable_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_readable__doc__,
+"readable($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_READABLE_METHODDEF    \
+    {"readable", (PyCFunction)_io__Buffered_readable, METH_NOARGS, _io__Buffered_readable__doc__},
+
+static PyObject *
+_io__Buffered_readable_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_readable(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_readable_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_writable__doc__,
+"writable($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_WRITABLE_METHODDEF    \
+    {"writable", (PyCFunction)_io__Buffered_writable, METH_NOARGS, _io__Buffered_writable__doc__},
+
+static PyObject *
+_io__Buffered_writable_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_writable(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_writable_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_fileno__doc__,
+"fileno($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_FILENO_METHODDEF    \
+    {"fileno", (PyCFunction)_io__Buffered_fileno, METH_NOARGS, _io__Buffered_fileno__doc__},
+
+static PyObject *
+_io__Buffered_fileno_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_fileno(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_fileno_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_isatty__doc__,
+"isatty($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_ISATTY_METHODDEF    \
+    {"isatty", (PyCFunction)_io__Buffered_isatty, METH_NOARGS, _io__Buffered_isatty__doc__},
+
+static PyObject *
+_io__Buffered_isatty_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_isatty(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_isatty_impl(self);
+}
+
+PyDoc_STRVAR(_io__Buffered_flush__doc__,
+"flush($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_FLUSH_METHODDEF    \
+    {"flush", (PyCFunction)_io__Buffered_flush, METH_NOARGS, _io__Buffered_flush__doc__},
+
+static PyObject *
+_io__Buffered_flush_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_flush(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_flush_impl(self);
+}
+
 PyDoc_STRVAR(_io__Buffered_peek__doc__,
 "peek($self, size=0, /)\n"
 "--\n"
@@ -490,6 +668,23 @@ _io__Buffered_readline(buffered *self, PyObject *const *args, Py_ssize_t nargs)
     return return_value;
 }
 
+PyDoc_STRVAR(_io__Buffered_tell__doc__,
+"tell($self, /)\n"
+"--\n"
+"\n");
+
+#define _IO__BUFFERED_TELL_METHODDEF    \
+    {"tell", (PyCFunction)_io__Buffered_tell, METH_NOARGS, _io__Buffered_tell__doc__},
+
+static PyObject *
+_io__Buffered_tell_impl(buffered *self);
+
+static PyObject *
+_io__Buffered_tell(buffered *self, PyObject *Py_UNUSED(ignored))
+{
+    return _io__Buffered_tell_impl(self);
+}
+
 PyDoc_STRVAR(_io__Buffered_seek__doc__,
 "seek($self, target, whence=0, /)\n"
 "--\n"
@@ -532,26 +727,41 @@ PyDoc_STRVAR(_io__Buffered_truncate__doc__,
 "\n");
 
 #define _IO__BUFFERED_TRUNCATE_METHODDEF    \
-    {"truncate", _PyCFunction_CAST(_io__Buffered_truncate), METH_FASTCALL, _io__Buffered_truncate__doc__},
+    {"truncate", _PyCFunction_CAST(_io__Buffered_truncate), METH_METHOD|METH_FASTCALL|METH_KEYWORDS, _io__Buffered_truncate__doc__},
 
 static PyObject *
-_io__Buffered_truncate_impl(buffered *self, PyObject *pos);
+_io__Buffered_truncate_impl(buffered *self, PyTypeObject *cls, PyObject *pos);
 
 static PyObject *
-_io__Buffered_truncate(buffered *self, PyObject *const *args, Py_ssize_t nargs)
+_io__Buffered_truncate(buffered *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
+    #if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
+    #  define KWTUPLE (PyObject *)&_Py_SINGLETON(tuple_empty)
+    #else
+    #  define KWTUPLE NULL
+    #endif
+
+    static const char * const _keywords[] = {"", NULL};
+    static _PyArg_Parser _parser = {
+        .keywords = _keywords,
+        .fname = "truncate",
+        .kwtuple = KWTUPLE,
+    };
+    #undef KWTUPLE
+    PyObject *argsbuf[1];
     PyObject *pos = Py_None;
 
-    if (!_PyArg_CheckPositional("truncate", nargs, 0, 1)) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 1, 0, argsbuf);
+    if (!args) {
         goto exit;
     }
     if (nargs < 1) {
-        goto skip_optional;
+        goto skip_optional_posonly;
     }
     pos = args[0];
-skip_optional:
-    return_value = _io__Buffered_truncate_impl(self, pos);
+skip_optional_posonly:
+    return_value = _io__Buffered_truncate_impl(self, cls, pos);
 
 exit:
     return return_value;
@@ -877,4 +1087,4 @@ _io_BufferedRandom___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=c4ea041ccc91b5d2 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=d770e392e8702e12 input=a9049054013a1b77]*/