code: function(width, height, block) {
      // Set default viewbox to match the width and height, set ref to cx and cy and set orient to auto
      return this.put(new SVG.Marker)
        .size(width, height)
        .ref(width / 2, height / 2)
        .viewbox(0, 0, width, height)
        .attr('orient', 'auto')
        .update(block)
    }
docs: Create marker