lighten function
Returns a lighter shade of color by raising HSL lightness by amount
(clamped to [0, 1]).
Implementation
Color lighten(Color color, [double amount = .1]) {
assert(amount >= 0 && amount <= 1);
final hsl = HSLColor.fromColor(color);
final hslLight = hsl.withLightness((hsl.lightness + amount).clamp(0.0, 1.0));
return hslLight.toColor();
}