function hexFromArgb(argb) {
    const r = redFromArgb(argb);
    const g = greenFromArgb(argb);
    const b = blueFromArgb(argb);
    const outParts = [r.toString(16), g.toString(16), b.toString(16)];
    // Pad single-digit output values
    for (const [i, part] of outParts.entries()) {
        if (part.length === 1) {
            outParts[i] = '0' + part;
        }
    }
    return '#' + outParts.join('');
}
@param argb ARGB representation of a color.
@return Hex string representing color, ex. #ff0000 for red.