<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def variant(self):
        '''Get the current theme variant'''
        variant = current_app.config['THEME_VARIANT']
        if variant not in self.variants:
            log.warning('Unkown theme variant: %s', variant)
            return 'default'
        else:
            return variant