gh-152315: Clarify missing self heuristic

Author: SurenNihalani

Python/ceval.c

@@ -1678,10 +1678,13 @@ suggest_missing_self(PyFunctionObject *func, PyCodeObject *co,
 
     PyObject *first_argument = PyStackRef_AsPyObjectBorrow(args[0]);
     if (first_argument == NULL || PyType_Check(first_argument)) {
+        // When first arg is NULL, it's not really about self
+        // If its a type object, then its a classmethod.
         return 0;
     }
 
     if (co->co_argcount > 0) {
+        // don't confuse the user when they've already declared a common convention of cls/self
         PyObject *first_parameter_name = PyTuple_GET_ITEM(co->co_localsplusnames, 0);
         /* If the receiver parameter is already declared, another hint would be misleading. */
         if (PyUnicode_CompareWithASCIIString(first_parameter_name, "self") == 0 ||
@@ -1690,7 +1693,7 @@ suggest_missing_self(PyFunctionObject *func, PyCodeObject *co,
             return 0;
         }
     }
-
+    // If the current function matches on the type, its likely worth adding the hint
     PyTypeObject *self_cls = Py_TYPE(first_argument);
     PyFunctionObject *possibly_current_function =
         (PyFunctionObject *)_PyType_Lookup(self_cls, co->co_name);