lighten method
Implementation
Color lighten([double amount = .1]) {
assert(amount >= 0 && amount <= 1, 'Amount must be between 0 and 1');
final hsl = HSLColor.fromColor(this);
final hslLight = hsl.withLightness(
(hsl.lightness + amount).clamp(
0.0,
1.0,
),
);
return hslLight.toColor();
}