[unified_order 支付统一下单函数](unified_order%E6%94%AF%E4%BB%98%E7%BB%9F%E4%B8%80%E4%B8%8B%E5%8D%95%E5%87%BD%E6%95%B0.md) [back 回调状态函数](back%E6%94%AF%E4%BB%98%E5%9B%9E%E8%B0%83%E5%A4%84%E7%90%86%E5%87%BD%E6%95%B0.md) [back_sign 回调签名验证函数](back_sign%E5%9B%9E%E8%B0%83%E7%AD%BE%E5%90%8D%E9%AA%8C%E8%AF%81%E5%87%BD%E6%95%B0.md) [back_currency 回调币种函数](back_currency%E5%9B%9E%E8%B0%83%E5%B8%81%E7%A7%8D%E5%87%BD%E6%95%B0.md) [back_bank 回调银行函数](back_bank%E5%9B%9E%E8%B0%83%E9%93%B6%E8%A1%8C%E5%87%BD%E6%95%B0.md)