index.js
function(color, amount) {
    var hsl = this.toHSL(color);

    hsl.s += amount / 100;
    hsl.s = clamp(hsl.s);
    return hsla(hsl);
  }
function(color, amount) {
    var hsl = this.toHSL(color);

    hsl.s += amount / 100;
    hsl.s = clamp(hsl.s);
    return hsla(hsl);
  }
function ( color , amount ) { var hsl = this . toHSL ( color ) ; hsl . s += amount / 100 ; hsl . s = clamp ( hsl . s ) ; return hsla ( hsl ) ; }
Saturate or desaturate a color by a given amount

@param {Color} color
@param {Number} amount
@returns {Color} color
Saturate or desaturate a color by a given amount