GDBusInterfaceVTable method_call ?

$ python
Python 2.7.3 (default, Apr 30 2012, 20:31:33)
[GCC 4.7.0 20120416 (Red Hat 4.7.0-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from gi.repository import Gio
>>> vtable = Gio.DBusInterfaceVTable()
>>> vtable.method_call

** (process:3806): WARNING **: Field method_call: Interface type 2 should have is_pointer set
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: unable to get the value
>>>