printUsage method
Prints the usage information for this command.
This is called internally by run and can be overridden by subclasses to control how output is displayed or integrate with a logging system.
Implementation
@override
void printUsage() {
final r = runner;
if (r is CommandRunner<T>) {
r.writeOut(formatUsage());
return;
}
dartio.stdout.writeln(formatUsage());
}