public function execute(InputInterface $input, OutputInterface $output)
{
$server = $input->getArgument('server');
$key = $input->getArgument('key');
$output->writeln("<info>Removing key `{$key}`</info>");
$client = new EtcdClient($server);
$data = $client->rm($key);
$json = json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
echo $json;
}