code: def to_line_string(self, closed=True):
          
          from imgaug.augmentables.lines import LineString
          if not closed or len(self.exterior) <= 1:
              return LineString(self.exterior, label=self.label)
          return LineString(
              np.concatenate([self.exterior, self.exterior[0:1, :]], axis=0),
              label=self.label)
docs: Convert this polygon's `exterior` to a ``LineString`` instance.
  
          Parameters
          ----------
          closed : bool, optional
              Whether to close the line string, i.e. to add the first point of
              the `exterior` also as the last point at the end of the line string.
              This has no effect if the polygon has a single point or zero
              points.
  
          Returns
          -------
          imgaug.augmentables.lines.LineString
              Exterior of the polygon as a line string.