code: def extend(self, all_sides=0, top=0, right=0, bottom=0, left=0):
          
          return BoundingBox(
              x1=self.x1 - all_sides - left,
              x2=self.x2 + all_sides + right,
              y1=self.y1 - all_sides - top,
              y2=self.y2 + all_sides + bottom
          )
docs: Extend the size of the bounding box along its sides.
  
          Parameters
          ----------
          all_sides : number, optional
              Value by which to extend the bounding box size along all sides.
  
          top : number, optional
              Value by which to extend the bounding box size along its top side.
  
          right : number, optional
              Value by which to extend the bounding box size along its right side.
  
          bottom : number, optional
              Value by which to extend the bounding box size along its bottom side.
  
          left : number, optional
              Value by which to extend the bounding box size along its left side.
  
          Returns
          -------
          imgaug.BoundingBox
              Extended bounding box.