code: def platypus(in_file, data):
      
      filters = ('(FR[0] <= 0.5 && TC < 4 && %QUAL < 20) || '
                 '(TC < 13 && %QUAL < 10) || '
                 '(FR[0] > 0.5 && TC < 4 && %QUAL < 50)')
      limit_regions = "variant_regions" if not vcfutils.is_gvcf_file(in_file) else None
      return cutoff_w_expression(in_file, filters, data, name="PlatQualDepth",
                                 extra_cmd="| sed 's/\\tQ20\\t/\\tPASS\\t/'", limit_regions=limit_regions)
docs: Filter Platypus calls, removing Q20 filter and replacing with depth and quality based filter.
  
      Platypus uses its own VCF nomenclature: TC == DP, FR == AF
  
      Platypus gVCF output appears to have an 0/1 index problem so the reference block
      regions are 1 base outside regions of interest. We avoid limiting regions during
      filtering when using it.