code: def _features_without_strokes(self, hwr_obj):
          
          x = []
          for point in hwr_obj.get_pointlist()[0]:
              if len(x) >= 3*self.points_per_stroke or \
                 (len(x) >= 2*self.points_per_stroke and not self.pen_down):
                  break
              x.append(point['x'])
              x.append(point['y'])
              if self.pen_down:
                  if 'pen_down' not in point:
                      logging.error("The "
                                    "ConstantPointCoordinates(strokes=0) "
                                    "feature should only be used after "
                                    "SpaceEvenly preprocessing step.")
                  else:
                      x.append(int(point['pen_down']))
          if self.pen_down:
              while len(x) != 3*self.points_per_stroke:
                  x.append(self.fill_empty_with)
          else:
              while len(x) != 2*self.points_per_stroke:
                  x.append(self.fill_empty_with)
          return x
docs: Calculate the ConstantPointCoordinates features for the case of
             a single (callapesed) stroke with pen_down features.