Setting -f option for vardict and var2vcf_valid
        Prioritizing settings in resources/vardict/options, then algorithm/min_allele_fraction:
    min_allele_fraction   "-f" in opts  var2vcfopts   ->   vardict -f            var2vcf -f
    yes                           yes   yes                opts                  var2vcfopts
    yes                           yes   -                  opts                  -
    yes                           -     yes                min_allele_fraction   var2vcfopts
    yes                           -     -                  min_allele_fraction   min_allele_fraction
    default                       yes   yes                opts                  var2vcfopts
    default                       yes   -                  opts                  -
    default                       -     yes                min_allele_fraction   var2vcfopts
    default                       -     -                  min_allele_fraction   min_allele_fraction

def _add_freq_options(config, opts, var2vcf_opts):
    """ Setting -f option for vardict and var2vcf_valid
        Prioritizing settings in resources/vardict/options, then algorithm/min_allele_fraction:
    min_allele_fraction   "-f" in opts  var2vcfopts   ->   vardict -f            var2vcf -f
    yes                           yes   yes                opts                  var2vcfopts
    yes                           yes   -                  opts                  -
    yes                           -     yes                min_allele_fraction   var2vcfopts
    yes                           -     -                  min_allele_fraction   min_allele_fraction
    default                       yes   yes                opts                  var2vcfopts
    default                       yes   -                  opts                  -
    default                       -     yes                min_allele_fraction   var2vcfopts
    default                       -     -                  min_allele_fraction   min_allele_fraction
    """
    if "-f" not in opts:
        freq = float(utils.get_in(config, ("algorithm", "min_allele_fraction"), 10)) / 100.0
        opts.extend(["-f", str(freq)])
        if "-f" not in var2vcf_opts:
            var2vcf_opts.extend(["-f", str(freq)])