code: function(){
  		var darkest,
  			minBrightness = Number.MAX_VALUE;
  		this.each(function(c){
  			var luma = c.luminance();
  			if(luma < minBrightness){
  				darkest = c;
  				minBrightness = luma;
  			}
  		});
  		return darkest;
  	}
docs: Finds and returns the darkest color of the list.
  @return darkest color or null if there're no entries yet.