ref check derived

{
  "input": {
    "type": "http",
    "method": "GET",
    "queryParams": {}
  },
  "output": {
    "type": "json",
    "errors": {
      "400": {
        "example": {
          "error": "invalid request"
        },
        "description": "Invalid or missing parameter(s). Returned before the payment gate on paid requests, so a malformed call is never charged. JSON body: { error: <what is wrong and how to fix it> } plus usage hints."
      },
      "402": {
        "description": "Payment required — x402 v2 challenge; the accepts array lists scheme, network, and amount. Retry the same request with a PAYMENT-SIGNATURE (v2) or X-PAYMENT (v1) header. Verification is free."
      },
      "500": {
        "example": {
          "error": "upstream_failed"
        },
        "description": "Unexpected server error. If a payment settled without a usable result, contact info@theaslangroupllc.com with the settlement tx hash for a re-run or credit."
      }
    },
    "example": {
      "checked": 3,
      "results": [
        {
          "input": "10.1016/S0140-6736(97)11096-0",
          "verdict": "retracted",
          "confidence": 0.98,
          "retraction": [
            {
              "date": "2010-02-06",
              "type": "retraction",
              "source": "retraction-watch",
              "notice_doi": "10.1016/s0140-6736(10)60175-4"
            }
          ],
          "is_retracted": true
        }
      ],
      "verified": 1,
      "not_found": 1,
      "retracted": 1
    }
  }
}