def lookupModel():
    """Return the IModel specified in either the model_source or
        model_file (the former takes precedence). See plone.supermodel for
        more information about this type.

        If neither a model_source or a model_file is given, but a schema is
        given, return a faux model that contains just this schema.

        Note that model.schema is not necessarily going to be the same as
        the schema returned by lookupSchema().
        """
