useDecoration method
Implementation
void useDecoration(NikuInputDecoration Function(NikuInputDecoration) v) {
if (decoration == null) decoration = NikuInputDecoration();
decoration?.apply = v(decoration!);
}
void useDecoration(NikuInputDecoration Function(NikuInputDecoration) v) {
if (decoration == null) decoration = NikuInputDecoration();
decoration?.apply = v(decoration!);
}