public function set($_, $assoc_args)
    {
        $this->init_args(func_get_args());
        list($key, $value) = $_;

        $env = $this->get_env_for_write_or_fail();
        $env->set($key, $value, $this->quote());
        $env->save();

        WP_CLI::success("'$key' set.");
    }