docs: def serialize(self):
          """Return string representation for VCF"""
          if self.mate_chrom is None:
              remote_tag = "."
          else:
              if self.within_main_assembly:
                  mate_chrom = self.mate_chrom
              else:
                  mate_chrom = "<{}>".format(self.mate_chrom)
              tpl = {FORWARD: "[{}:{}[", REVERSE: "]{}:{}]"}[self.mate_orientation]
              remote_tag = tpl.format(mate_chrom, self.mate_pos)
          if self.orientation == FORWARD:
              return remote_tag + self.sequence
          else:
              return self.sequence + remote_tag