====> query single signature result: 
object(Qiniu\Http\Error)#6 (2) {
  ["url":"Qiniu\Http\Error":private]=>
  string(44) "https://sms.qiniuapi.com/v1/signature/xxxxxx"
  ["response":"Qiniu\Http\Error":private]=>
  object(Qiniu\Http\Response)#7 (7) {
    ["statusCode"]=>
    int(-1)
    ["headers"]=>
    array(0) {
    }
    ["normalizedHeaders"]=>
    NULL
    ["body"]=>
    NULL
    ["error"]=>
    string(63) "SSL certificate problem: unable to get local issuer certificate"
    ["jsonData":"Qiniu\Http\Response":private]=>
    NULL
    ["duration"]=>
    float(0.082)
  }
}