def position=(val)
      if @enable_pen
        @enable_pen = false
        left = x + center_x
        top = y + center_y
        self.x = val[0]
        self.y = val[1]
        draw_pen(left, top, x + center_x, y + center_y)
        @enable_pen = true
      else
        self.x = val[0]
        self.y = val[1]
      end
    end
def position=(val)
      if @enable_pen
        @enable_pen = false
        left = x + center_x
        top = y + center_y
        self.x = val[0]
        self.y = val[1]
        draw_pen(left, top, x + center_x, y + center_y)
        @enable_pen = true
      else
        self.x = val[0]
        self.y = val[1]
      end
    end
X座標を(  )、Y座標を(  )にする