code: public function apply(array $options)
      {
          unset($this->config['trade_type']);
          unset($this->config['notify_url']);
          $this->config = array_merge($this->config, $options);
          $this->config['sign'] = $this->getSign($this->config);
          return $this->post($this->gateway_bill, $this->toXml($this->config));
      }
docs: 应用并返回参数
  @param array $options
  @return bool|string