src/Application.php
public function config(string $key, $default = null)
    {
        return $this->container->get(Config::class)->get($key, $default);
    }
public function config(string $key, $default = null)
    {
        return $this->container->get(Config::class)->get($key, $default);
    }
Get a config key

@param string $key
@param mixed $default
@return mixed