code: function WidgetKnob() {
          this.addOutput("", "number");
          this.size = [64, 84];
          this.properties = {
              min: 0,
              max: 1,
              value: 0.5,
              color: "#7AF",
              precision: 2
          };
          this.value = -1;
      }
docs: /* Knob ***************