### Connect to Discord Gateway and Reply to Mentions

Source: https://pub.dev/packages/nyxx/documentation/packages/nyxx

Demonstrates connecting to the Discord gateway using `Nyxx.connectGateway` with all unprivileged intents. It fetches the current bot user and sets up a listener for `onMessageCreate` events to reply when the bot is mentioned in a message. The example uses `MessageBuilder` and `MessageReferenceBuilder` for constructing and replying to messages.

```dart
import 'package:nyxx/nyxx.dart';

void main() async {
  final client = await Nyxx.connectGateway('<TOKEN>', GatewayIntents.allUnprivileged);

  final botUser = await client.users.fetchCurrentUser();

  client.onMessageCreate.listen((event) async {
    if (event.mentions.contains(botUser)) {
      await event.message.channel.sendMessage(MessageBuilder(
        content: 'You mentioned me!',
        referencedMessage: MessageReferenceBuilder.reply(messageId: event.message.id),
      ));
    }
  });
}
```

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