registry method
Implementation
VoidCallback registry(T value) {
assert(value != null, 'value must not be null.');
_sets.add(value);
return () {
_sets.remove(value);
};
}
VoidCallback registry(T value) {
assert(value != null, 'value must not be null.');
_sets.add(value);
return () {
_sets.remove(value);
};
}