code: def _replace_bbox_none(self, bbox):
          
  
          (bb_top, bb_left), (bb_bottom, bb_right) = bbox
  
          if bb_top is None:
              bb_top = 0
  
          if bb_left is None:
              bb_left = 0
  
          if bb_bottom is None:
              bb_bottom = self.code_array.shape[0] - 1
  
          if bb_right is None:
              bb_right = self.code_array.shape[1] - 1
  
          return (bb_top, bb_left), (bb_bottom, bb_right)
docs: Returns bbox, in which None is replaced by grid boundaries