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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def metadata(self, filename):
        '''
        Fetch all available metadata for a given file
        '''
        meta = self.get_metadata(filename)
        # Fix backend mime misdetection
        meta['mime'] = meta.get('mime') or files.mime(filename, self.DEFAULT_MIME)
        return meta