code: def blast(self, blastfile=None, outfile=None):
          
          from jcvi.formats.blast import BlastSlow, BlastLineByConversion
  
          if not outfile:
              outfile = self.filename + ".blast"
  
          if blastfile is not None:
              blasts = BlastSlow(blastfile).to_dict()
          else:
              blasts = None
  
          fw = must_open(outfile, "w", checkexists=True)
          nlines = 0
          for a, b, id in self.iter_pairs():
              if (a, b) in blasts:
                  bline = blasts[(a, b)]
              elif (b, a) in blasts:
                  bline = blasts[(b, a)]
              else:
                  line = "\t".join((a, b))
                  bline = BlastLineByConversion(line, mode="110000000000")
  
              print(bline, file=fw)
              nlines += 1
          fw.close()
  
          logging.debug("A total of {0} BLAST lines written to `{1}`."\
                          .format(nlines, outfile))
  
          return outfile
docs: convert anchor file to 12 col blast file