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const oneSecond = Duration(seconds: 1);
// ...
Future<void> printWithDelay(String message) async {
await Future.delayed(oneSecond);
print(message);
}
Future<void> printWithDelay(String message) {
return Future.delayed(oneSecond).then((_) {
print(message);
});
}
Future<void> createDescriptions(Iterable<String> objects) async {
for (var object in objects) {
try {
var file = File('$object.txt');
if (await file.exists()) {
var modified = await file.lastModified();
print('File for $object already exists. It was modified on $modified.');
continue;
}
await file.create();
await file.writeAsString('Start describing $object in this file.');
} on IOException catch (e) {
print('Cannot create description for $object: $e');
}
}
}
Stream<String> report(Spacecraft craft, Iterable<String> objects) async* {
for (var object in objects) {
await Future.delayed(oneSecond);
yield '${craft.name} flies by $object';
}
}
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