Removed the API to create unbound methods and simplified the API for bound methods. The signature is PyMethod_New(func, instance).
Also removed im_class and renamed im_self to __self__ and im_func to __func__. im_class can be substituted with method.__self__.__class__.
I've also updated some parts of the documenation.
diff --git a/Include/classobject.h b/Include/classobject.h
index 885c43e..e6ca421 100644
--- a/Include/classobject.h
+++ b/Include/classobject.h
@@ -1,4 +1,4 @@
-/* Former class object interface -- now only (un)bound methods are here  */
+/* Former class object interface -- now only bound methods are here  */
 
 /* Revealing some structures (not for general use) */
 
@@ -11,8 +11,7 @@
 typedef struct {
     PyObject_HEAD
     PyObject *im_func;   /* The callable object implementing the method */
-    PyObject *im_self;   /* The instance it is bound to, or NULL */
-    PyObject *im_class;  /* The class that asked for the method */
+    PyObject *im_self;   /* The instance it is bound to */
     PyObject *im_weakreflist; /* List of weak references */
 } PyMethodObject;
 
@@ -20,7 +19,7 @@
 
 #define PyMethod_Check(op) ((op)->ob_type == &PyMethod_Type)
 
-PyAPI_FUNC(PyObject *) PyMethod_New(PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(PyObject *) PyMethod_New(PyObject *, PyObject *);
 
 PyAPI_FUNC(PyObject *) PyMethod_Function(PyObject *);
 PyAPI_FUNC(PyObject *) PyMethod_Self(PyObject *);
@@ -32,8 +31,6 @@
         (((PyMethodObject *)meth) -> im_func)
 #define PyMethod_GET_SELF(meth) \
 	(((PyMethodObject *)meth) -> im_self)
-#define PyMethod_GET_CLASS(meth) \
-	(((PyMethodObject *)meth) -> im_class)
 
 #ifdef __cplusplus
 }