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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 to_dict(self):
 """ Returns a dictionary of the essential fields of this Genome. """

        return dict(
            reference_name=self.reference_name,
            annotation_name=self.annotation_name,
            annotation_version=self.annotation_version,
            gtf_path_or_url=self._gtf_path_or_url,
            transcript_fasta_paths_or_urls=self._transcript_fasta_paths_or_urls,
            protein_fasta_paths_or_urls=self._protein_fasta_paths_or_urls,
            decompress_on_download=self.decompress_on_download,
            copy_local_files_to_cache=self.copy_local_files_to_cache,
            cache_directory_path=self.cache_directory_path)