getPreview method
Implementation
Stream<List<int>> getPreview(String id) async* {
final url = Uri.parse('${baseUrl}api/files/previews/$id');
final streamedResponse = await client.send(http.Request('GET', url));
if (streamedResponse.statusCode != 200) {
final response = await http.Response.fromStream(streamedResponse);
throw MailosaurError(response);
}
yield* streamedResponse.stream;
}