code: def _dy(self):
          
          min_y = max_y = self._start_y
          for drawing_operation in self:
              if hasattr(drawing_operation, 'y'):
                  min_y = min(min_y, drawing_operation.y)
                  max_y = max(max_y, drawing_operation.y)
          return max_y - min_y
docs: Return integer height of this shape's path in local units.