docs: def circle(rad=0.5):
      """Draw a circle"""
      _ctx = _state["ctx"]
      _ctx.arc(0, 0, rad, 0, 2 * math.pi)
      _ctx.set_line_width(0)
      _ctx.stroke_preserve()
      # _ctx.set_source_rgb(0.3, 0.4, 0.6)
      _ctx.fill()