1. @override
Future<int> handle()

Handles the command input.

Override this method to perform actions for this command.

Return value is the value returned to the command line operation. Return 0 for success.

Source 

@override
Future<int> handle() async {
  if (shouldSetupHeroku) {
    return setupHerokuProject();
  } else /*if (shouldSetupTests*/ {
    return setupTestEnvironment();
  }
}