code: def _select_final_variants(base_vcf, out_vcf, config):
      
      min_depth = int(config["algorithm"].get("min_depth", 4))
      with file_transaction(out_vcf) as tx_out_file:
          with open(base_vcf) as in_handle:
              with open(tx_out_file, "w") as out_handle:
                  for line in in_handle:
                      if line.startswith("#"):
                          passes = True
                      else:
                          passes = _passes_cortex_depth(line, min_depth)
                      if passes:
                          out_handle.write(line)
      return out_vcf
docs: Filter input file, removing items with low depth of support.
  
      cortex_var calls are tricky to filter by depth. Count information is in
      the COV FORMAT field grouped by alleles, so we need to sum up values and
      compare.