code: def center(self) -> Location:
          
          top = self.top()
          center_z = top.point.z - (self._depth / 2.0)
          return Location(Point(x=top.point.x, y=top.point.y, z=center_z), self)
docs: :return: a Point corresponding to the absolute position of the center
          of the well relative to the deck (with the front-left corner of slot 1
          as (0,0,0))