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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 use_vqsr(algs, call_file=None):
 """Processing uses GATK's Variant Quality Score Recalibration. """

    from bcbio.variation import vcfutils
    vqsr_callers = set(["gatk", "gatk-haplotype"])
    vqsr_sample_thresh = 50
    vqsr_supported = collections.defaultdict(int)
    coverage_intervals = set([])
    for alg in algs:
        callers = alg.get("variantcaller")
        if isinstance(callers, six.string_types):
            callers = [callers]
        if not callers:  # no variant calling, no VQSR
            continue
        if "vqsr" in (alg.get("tools_off") or []):  # VQSR turned off
            continue
        for c in callers:
            if c in vqsr_callers:
                if "vqsr" in (alg.get("tools_on") or []):  # VQSR turned on:
                    vqsr_supported[c] += 1
                    coverage_intervals.add("genome")
                # Do not try VQSR for gVCF inputs
                elif call_file and vcfutils.is_gvcf_file(call_file):
                    pass
                else:
                    coverage_intervals.add(alg.get("coverage_interval", "exome").lower())
                    vqsr_supported[c] += 1
    if len(vqsr_supported) > 0:
        num_samples = max(vqsr_supported.values())
        if "genome" in coverage_intervals or num_samples >= vqsr_sample_thresh:
            return True
    return False