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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 _calculate_sv_coverage_gatk(data, work_dir):
 """Calculate coverage in defined regions using GATK tools TODO: This does double calculations to get GATK4 compatible HDF read counts and then depth and gene annotations. Both are needed for creating heterogeneity inputs. Ideally replace with a single mosdepth coverage calculation, and creat GATK4 TSV format: CONTIG START END COUNT chrM 1 1000 13268 """

    from bcbio.variation import coverage
    from bcbio.structural import annotate
    # GATK compatible
    target_file = gatkcnv.collect_read_counts(data, work_dir)
    # heterogeneity compatible
    target_in = bedutils.clean_file(tz.get_in(["regions", "bins", "target"], data), data, bedprep_dir=work_dir)
    target_cov = coverage.run_mosdepth(data, "target-gatk", target_in)
    target_cov_genes = annotate.add_genes(target_cov.regions, data, max_distance=0)
    return target_file, target_cov_genes