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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 _fields(self):
 """ Fields used for hashing, string representation, equality comparison """

        return (
            ('reference_name', self.reference_name,),
            ('annotation_name', self.annotation_name),
            ('annotation_version', self.annotation_version),
            ('cache_directory_path', self.cache_directory_path),
            ('decompress_on_download', self.decompress_on_download),
            ('copy_local_files_to_cache', self.copy_local_files_to_cache)
        )