private static ArrayList<String> canProduce(int maxChoices, Ability_Mana ab, ArrayList<String> colors) {
        for (String col : Constant.Color.onlyColors) {
            String s = Input_PayManaCostUtil.getShortColorString(col);
            if (ab.canProduce(s) && !colors.contains(col))
                colors.add(col);
        }

        if (maxChoices == 6 && ab.canProduce("1") && !colors.contains(Constant.Color.Colorless))
            colors.add(Constant.Color.Colorless);

        return colors;
    }