/// color code type
enum ColorCodeType: Int {
    case hex          // #ffffff
    case hexWithAlpha // #ffffffff
    case shortHex     // #fff
    case cssRGB       // rgb(255,255,255)
    case cssRGBa      // rgba(255,255,255,1)
    case cssHSL       // hsl(0,0%,100%)
    case cssHSLa      // hsla(0,0%,100%,1)
    case cssKeyword   // White
};

import ColorCode
// create NSColor instance from HSLa color code
var type: ColorCodeType?
let whiteColor = NSColor(colorCode: "hsla(0,0%,100%,0.5)", type: &type)
let hex: String = whiteColor.colorCode(type: .hex)  // => "#ffffff"
// create NSColor instance from HSLa values
let color = NSColor(deviceHue:0.1, saturation:0.2, lightness:0.3, alpha:1.0)
// create NSColor instance from a CSS3 keyword
let ivoryColor = NSColor(colorCode: "ivory")
// get HSL values from NSColor instance
var hue: CGFloat = 0
var saturation: CGFloat = 0
var lightness: CGFloat = 0
var alpha: CGFloat = 0
color.getHue(hue: &hue, saturation: &saturation, lightness: &lightness, alpha: &alpha)