code: public GenericColor darken(ColorFactor factor) {
  
      return valueOf(this.red.decrease(factor), this.green.decrease(factor), this.blue.decrease(factor), this.alpha);
    }
docs: Darkens this color by the given {@code factor}.
  
  @param factor is the factor to decrease by. E.g. {@code 0.0} will cause no change, while {@code 1.0} will return
  {@link Color#BLACK black}.
  @return a new color darker by the given {@code factor}.