If the parameters are wrapped in curly braces, it means they are still optional, but they are now named parameters. The name is now required when calling the function.

examples/intro/prompt_named.dart
String prompt(String text, {int count}) {
  if (count == null) {
    count = 1;
  }
  for (int i = 0; i < count; i++) {
    print(text);
  }
}

void main() {
    prompt("Your name:", count:3);
    prompt("Your Cat:");
}