docs: def liftover(self, origin, dest, o_start, o_end, trim=False):
      """liftover interval in one seq. of this pairwise alignment to the other.
  
      :param origin:  name of the origin seq (seq the input coordinates are for)
      :param dest:    name of the dest. seq (seq the result will be for)
      :param o_start: start of the interval (in sequence co-ordinates) to lift.
      :param o_end:   end of the interval (in seq. coords) to lift.
      """
      alig_cols = self.sequence_to_alignment_coords(origin, o_start,
                                                    o_end, trim=trim)
      res = []
      for s, e in alig_cols:
        t = self.alignment_to_sequence_coords(dest, s, e)
        if t is None:
          continue
        res.append(t)
      return res