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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 _get_data_versions(data):
 """Retrieve CSV file with version information for reference data. """

    genome_dir = install.get_genome_dir(data["genome_build"], data["dirs"].get("galaxy"), data)
    if genome_dir:
        version_file = os.path.join(genome_dir, "versions.csv")
        if version_file and os.path.exists(version_file):
            return version_file
    return None