code: def spv_freq_filter(line, tumor_index):
      
      if line.startswith("#CHROM"):
          headers = [('##FILTER=<ID=SpvFreq,Description="High frequency (tumor FREQ > 0.35) '
                      'and low p-value for somatic (SPV < 0.05)">')]
          return "\n".join(headers) + "\n" + line
      elif line.startswith("#"):
          return line
      else:
          parts = line.split("\t")
          sample_ft = {a: v for (a, v) in zip(parts[8].split(":"), parts[9 + tumor_index].split(":"))}
          freq = utils.safe_to_float(sample_ft.get("FREQ"))
          spvs = [x for x in parts[7].split(";") if x.startswith("SPV=")]
          spv = utils.safe_to_float(spvs[0].split("=")[-1] if spvs else None)
          fname = None
          if spv is not None and freq is not None:
              if spv < 0.05 and freq > 0.35:
                  fname = "SpvFreq"
          if fname:
              if parts[6] in set([".", "PASS"]):
                  parts[6] = fname
              else:
                  parts[6] += ";%s" % fname
          line = "\t".join(parts)
          return line
docs: Filter VarScan calls based on the SPV value and frequency.
  
      Removes calls with SPV < 0.05 and a tumor FREQ > 0.35.
  
      False positives dominate these higher frequency, low SPV calls. They appear
      to be primarily non-somatic/germline variants not removed by other filters.