def draw_oval(x, y, width, height)
      @context.drawOval(x, y, width, height)
    end
def draw_oval(x, y, width, height)
      @context.drawOval(x, y, width, height)
    end
Draws the largest oval that will fit in the specified rectangle.  The top left corner of the bounding
 rectangle is at (x, y).  The center of the oval will be at (x + width/2, y + height/2).