@classmethod
def _ap_compute_external_class_name_from_interface_and_instance(cls,
    unused_iface, impl):
    """
        Assigned as the tagged value ``__external_class_name__`` to each
        interface. This will be called on an instance implementing iface.

        .. seealso:: :class:`~.InterfaceObjectIO`
        """
    return cls._ap_compute_external_class_name_from_concrete_class(impl.
        __class__)
