lighten method
Lightens the color by amount
(0.0 to 1.0)
Implementation
Color lighten([double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(this);
final hslLight = hsl.withLightness((hsl.lightness + amount).clamp(0.0, 1.0));
return hslLight.toColor();
}