def verify_integrity(self):
        '''
        verify the integrity of the current option set

        @raises - ArgError if the options are invalid
        '''
        if snap.config.options.mode == None: # mode not specified
            raise snap.exceptions.ArgError("Must specify backup or restore")
        if snap.config.options.snapfile == None: # need to specify snapfile location
            raise snap.exceptions.ArgError("Must specify snapfile")
        # TODO verify output format is one of permitted types
        if snap.config.options.outputformat == None: # need to specify output format
            raise snap.exceptions.ArgError("Must specify valid output format")