How to use the color-string.keyword function in color-string

// set using rgb value
        pixelcolor = options.rgb || null;
    } else {
        return pixel.color;
    }

    if (pixelcolor != null) {
        // fill out the values for the pixel and then send the message to update
        // it on the strip

        with (pixel.color) {
            r = pixelcolor[0];
            g = pixelcolor[1];
            b = pixelcolor[2];
            hexcode = ColorString.hexString(pixelcolor);
            color = ColorString.keyword(pixelcolor);
            rgb = pixelcolor;
        }

        color = ColorString.colorValue(pixelcolor);
        if (sendmsg) {
            var msg = "{" + pixel.addr + ":" + color + "}";
            pixel.firmata.sp.write(makeSysExString(msg));
        }
    } else {
        console.log("color supplied couldn't be parsed: " + pixelcolor);
    }
};

keyword: function () {
		return string.keyword(this.values.rgb, this.values.alpha);
	},

keyword: function () {
		return string.keyword(this.values.rgb, this.values.alpha);
	},

keyword: function() {
      return string.keyword(this.values.rgb, this.values.alpha);
   },

keyword: function() {
         return string.keyword(values.rgb, values.alpha);
      },

keyword: function() {
      return string.keyword(this.values.rgb, this.values.alpha);
   },

keyword: function() {
      return string.keyword(this.values.rgb, this.values.alpha);
   },

keyword: function() {
      return string.keyword(this.values.rgb, this.values.alpha);
   },

keyword: function () {
		return string.keyword(this.values.rgb, this.values.alpha);
	},