def __init__(self, **kwargs):
        super(CleverCSS, self).__init__(**kwargs)
        assert self.filetype == 'css', (
            'CleverCSS only supports compilation to css. '
            'The parent filter expects "%s".' % self.filetype)
        self.input_filetype = 'clevercss'
dataset/ETHPy150Open adieu/django-mediagenerator/mediagenerator/filters/clever.py/CleverCSS.__init__/original