Calculate gross to net values

curl --request POST \
  --url https://api.sandbox.flowpayroll.ai/v1/calculator/grosstonet \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-Token: <api-key>' \
  --data '
{
  "taxCode": "1257L",
  "gross": 123,
  "period": 123,
  "niCategory": "A",
  "postGradLoanPlan": true,
  "grossToDate": 123,
  "week1Month1": true,
  "taxToDate": 1000
}
'

{
  "message": {
    "text": "<string>",
    "token": "<string>",
    "tokenArguments": [
      {
        "name": "<string>",
        "value": "<string>"
      }
    ]
  },
  "content": {
    "data": {
      "taxForPeriod": 123,
      "employeeNi": 123,
      "employerNi": 123,
      "studentLoan": 123,
      "postGradLoan": 123,
      "netPay": 123
    },
    "metadata": {
      "dateFormat": "yyyy-MM-dd",
      "dateTimeFormat": "yyyy-MM-ddTHH:mm:ss.fffZ",
      "paginationToken": "<string>"
    }
  },
  "validationIssues": [
    {
      "field": "<string>",
      "reason": "<string>",
      "reasonToken": "<string>",
      "reasonTokenArguments": [
        {
          "name": "<string>",
          "value": "<string>"
        }
      ]
    }
  ],
  "messageToken": "<string>"
}