review

Author: StanFromIreland

Doc/c-api/type.rst

@@ -138,6 +138,7 @@ Type Objects
    Return non-zero if the type object *type* sets the subclass flag *flag*.
    Subclass flags are denoted by
    :c:macro:`Py_TPFLAGS_*_SUBCLASS <Py_TPFLAGS_LONG_SUBCLASS>`.
+   This function is used by most ``_Check`` functions.
 
 
 .. c:function:: int PyType_IS_GC(PyTypeObject *o)

Doc/c-api/typeobj.rst

@@ -1351,8 +1351,8 @@ and :c:data:`PyType_Type` effectively act as defaults.)
    .. c:macro:: Py_TPFLAGS_BASE_EXC_SUBCLASS
    .. c:macro:: Py_TPFLAGS_TYPE_SUBCLASS
 
-      These flags are used by functions such as :c:func:`PyType_FastSubclass` and
-      :c:func:`PyLong_Check` to quickly determine if a type is a subclass
+      Functions such as :c:func:`PyLong_Check` will call :c:func:`PyType_FastSubclass`
+      with one of these flags to quickly determine if a type is a subclass
       of a built-in type; such specific checks are faster than a generic
       check, like :c:func:`PyObject_IsInstance`. Custom types that inherit
       from built-ins should have their :c:member:`~PyTypeObject.tp_flags`