public static String rainbowText(String data) {
        StringBuilder builder = new StringBuilder();
        for(int i = 0; i < data.length(); i++) {
            float hue = map(i, 0F, data.length(), 0.1F, 1F);
            float saturation = 0.6f; //saturation
            float brightness = 1f; //brightness
            Color color = Color.getHSBColor(hue, saturation, brightness);
            builder.append(String.format("#%s#%s", Integer.toHexString(-color.getRGB()), data.charAt(i)));
        }
        return builder.toString();
    }

    public static final float map(float value, float minValue, float maxValue, float minExpectedValue, float maxExpectedValue) {
        return minExpectedValue + (maxExpectedValue - minExpectedValue) * ((value - minValue) / (maxValue - minValue));
    }