docs: def _check_data(self):
          """Check if the data given is valid"""
          if self.axes is None:
              raise PolygonFilterError("`axes` parm not set.")
          if self.points is None:
              raise PolygonFilterError("`points` parm not set.")
          self.points = np.array(self.points)
          if self.points.shape[1] != 2:
              raise PolygonFilterError("data points' shape[1] must be 2.")
          if self.name is None:
              self.name = "polygon filter {}".format(self.unique_id)
          if not isinstance(self.inverted, bool):
              raise PolygonFilterError("`inverted` must be boolean.")