def rc_notfound(cls, interface_type, resource_name=None):
        """Exception used when no resource class is provided and no default is found.
        """

        msg = "Resource class for %s not provided and default not found." % interface_type

        if resource_name:
            msg = "Could not parse '%s'. %s" % (resource_name, msg)

        return cls(msg)
Exception used when no resource class is provided and no default is found.