def _variant_sv(checkpoints):
    """Structural variant workflow.
    """
    if not checkpoints.get("sv"):
        return [], []
    sv = [s("detect_sv", "batch-single",
            [["sv_batch_rec"]],
            [cwlout("sv_rec", "record",
                    fields=[cwlout(["sv", "variantcaller"], ["string", "null"]),
                            cwlout(["sv", "vrn_file"], ["File", "null"], [".tbi"]),
                            cwlout(["sv", "supplemental"], {"type": "array", "items": ["File"]}),
                            cwlout(["svvalidate", "summary"], ["File", "null"]),
                            cwlout("inherit", exclude=[["align_bam"], ["work_bam_plus"],
                                                       ["reference", "snpeff"]])])],
            "bcbio-vc", ["bedtools", "cnvkit", "delly", "duphold", "extract-sv-reads", "gsort",
                         "lumpy-sv;env=python2", "manta;env=python2", "break-point-inspector", "mosdepth", "samtools",
                         "smoove;env=python2", "pysam>=0.13.0",
                         "seq2c", "simple_sv_annotation;env=python2", "survivor", "svtools;env=python2",
                         "svtyper;env=python2",
                         "r=3.5.1", "r-base", "xorg-libxt", "vawk;env=python2"],
            disk={"files": 2.0})]
    sv_batch_inputs = [["analysis"], ["genome_build"],
                       ["work_bam_plus", "disc"], ["work_bam_plus", "sr"],
                       ["config", "algorithm", "background", "cnv_reference"],
                       ["config", "algorithm", "tools_on"],
                       ["config", "algorithm", "tools_off"],
                       ["config", "algorithm", "svprioritize"],
                       ["config", "algorithm", "svvalidate"], ["regions", "sample_callable"],
                       ["genome_resources", "variation", "gc_profile"],
                       ["genome_resources", "variation", "germline_het_pon"],
                       ["genome_resources", "aliases", "snpeff"], ["reference", "snpeff", "genome_build"],
                       ["sv_coverage_rec"]]
    if checkpoints.get("vc"):
        sv_batch_inputs.append(["variants", "samples"])
    steps = [s("calculate_sv_bins", "multi-combined",
               [["align_bam"], ["reference", "fasta", "base"],
                ["metadata", "batch"], ["metadata", "phenotype"],
                ["config", "algorithm", "background", "cnv_reference"],
                ["config", "algorithm", "callable_regions"],
                ["config", "algorithm", "coverage_interval"],
                ["config", "algorithm", "exclude_regions"],
                ["config", "algorithm", "sv_regions"],
                ["config", "algorithm", "variant_regions"],
                ["config", "algorithm", "variant_regions_merged"],
                ["config", "algorithm", "seq2c_bed_ready"],
                ["config", "algorithm", "svcaller"],
                ["depth", "variant_regions", "regions"],
                ["genome_resources", "variation", "lcr"], ["genome_resources", "variation", "polyx"],
                ["genome_resources", "variation", "encode_blacklist"],
                ["genome_resources", "rnaseq", "gene_bed"]],
               [cwlout("sv_bin_rec", "record",
                       fields=[cwlout(["regions", "bins", "target"], ["File", "null"]),
                               cwlout(["regions", "bins", "antitarget"], ["File", "null"]),
                               cwlout(["regions", "bins", "gcannotated"], ["File", "null"]),
                               cwlout(["regions", "bins", "group"], ["string", "null"]),
                               cwlout("inherit")])],
               "bcbio-vc", ["bedtools", "cnvkit"],
               disk={"files": 1.5}, cores=1),
             s("calculate_sv_coverage", "multi-parallel",
               [["sv_bin_rec"]],
               [cwlout("sv_rawcoverage_rec", "record",
                       fields=[cwlout(["depth", "bins", "target"], ["File", "null"]),
                               cwlout(["depth", "bins", "antitarget"], ["File", "null"]),
                               cwlout(["depth", "bins", "seq2c"], ["File", "null"]),
                               cwlout("inherit")])],
               "bcbio-vc", ["mosdepth", "cnvkit", "seq2c"],
               disk={"files": 1.5}),
             s("normalize_sv_coverage", "multi-combined",
               [["sv_rawcoverage_rec"]],
               [cwlout("sv_coverage_rec", "record",
                       fields=[cwlout(["depth", "bins", "normalized"], ["File", "null"]),
                               cwlout(["depth", "bins", "background"], ["File", "null"]),
                               cwlout("inherit")])],
               "bcbio-vc", ["cnvkit"],
               disk={"files": 1.5}),
             s("batch_for_sv", "multi-batch", sv_batch_inputs,
               [cwlout("sv_batch_rec", "record")],
               "bcbio-vc",
               unlist=[["config", "algorithm", "svcaller"]]),
             w("svcall", "multi-parallel", sv, []),
             s("summarize_sv", "multi-combined",
               [["sv_rec"]],
               [cwlout(["sv", "calls"], {"type": "array", "items": ["File", "null"]}),
                cwlout(["sv", "supplemental"], {"type": "array", "items": ["File"]}),
                cwlout(["sv", "prioritize", "tsv"], {"type": "array", "items": ["File", "null"]}),
                cwlout(["sv", "prioritize", "raw"], {"type": "array", "items": ["File", "null"]}),
                cwlout(["svvalidate", "grading_summary"], ["File", "null"]),
                cwlout(["svvalidate", "grading_plots"], {"type": "array", "items": ["File", "null"]})],
               "bcbio-vc", ["bcbio-prioritize"], disk={"files": 1.0}, cores=1)]
    final_outputs = [["sv", "calls"], ["svvalidate", "grading_summary"], ["sv", "prioritize", "tsv"],
                     ["sv", "prioritize", "raw"], ["sv", "supplemental"]]
    return steps, final_outputs