{
  "req": "post",
  "op": {
    "type": "updateLeverages",
    "args": [
      {
        "iid": 1,
        "lev": 10,
        "cross": true
      }
    ]
  },
  "sig": "0x1234567890...",
  "salt": 1234567890,
  "ts": 1767225600000
}

{
  "id": 7,
  "data": [
    {
      "status": "ok",
      "instrument_id": 1,
      "leverage": 5,
      "cross": false
    },
    {
      "status": "err",
      "instrument_id": 2,
      "error": "insufficient_margin"
    }
  ]
}