operator []= method
Implementation
void operator []=(String key, Object? value) {
if (value == null && !_map.containsKey(key)) return;
if (_map[key] == value) return;
if (value == null) {
_map.remove(key);
} else {
_map[key] = value;
}
try {
_file.writeAsStringSync('${_jsonEncoder.convert(_map)}\n');
} catch (_) {}
}