How to prevent signers from reassigning the document?

curl -X 'POST' \ 'https://api.boldsign.com/v1/document/send' \
     -H 'accept: application/json' \
     -H 'X-API-KEY: {your API key}' \
     -H 'Content-Type: multipart/form-data' \
     -F 'EnableReassign= false' \
     -F 'Message=' \
     -F 'Signers={
        "name": "Hanky",
        "emailAddress": "hankyWhites@cubeflakes.com",
        "signerType": "Signer",
        "formFields": [
           {
                "id": "string",
                "name": "string",
                "fieldType": "Signature",
                "pageNumber": 1,
                "bounds": {
                  "x": 50,
                  "y": 50,
                  "width": 1,
                  "height": 1
                   },
      "isRequired": true
    }
  ],
  "locale": "EN"
}' \
  -F 'Files={your file}' \
  -F 'Title={title}' \

var apiClient = new ApiClient("https://api.boldsign.com", "{your API key}");
var documentClient = new DocumentClient(apiClient);

var documentFilePath = new DocumentFilePath
{
   ContentType = "application/pdf",
   FilePath = "{Your file path}", 
};

var filesToUpload = new List<IDocumentFile>
{
    documentFilePath,
};

var signatureField = new FormField(
   id: "sign",
   isRequired: true,
   type: FieldType.Signature,
   pageNumber: 1,
   bounds: new Rectangle(x: 100, y: 100, width: 100, height: 50));

var formFieldCollections = new List<FormField>()
{
    signatureField
};

var signer = new DocumentSigner(
  signerName: "David",
  signerEmail: "david@cubeflakes.com",
  formFields: formFieldCollections,
  locale: Locales.EN);


var documentSigners = new List<DocumentSigner>()
{
    signer
};

var sendForSign = new SendForSign()
{
   Message = "please sign this",
   Title = "Agreement",
   EnableReassign = false,
   Signers = documentSigners,
   Files = filesToUpload
};
var documentCreated = documentClient.SendDocument(sendForSign);

import requests
import json

url = "https://api.boldsign.com/v1/document/send"

signer_data = {
    "name": "Hanky",
    "emailAddress": "hankyWhites@cubeflakes.com",
    "signerType": "Signer",
    "formFields": [
        {
            "id": "string",
            "name": "string",
            "fieldType": "Signature",
            "pageNumber": 1,
            "bounds": {
                "x": 50,
                "y": 50,
                "width": 1,
                "height": 1
            },
            "isRequired": True
        }
    ],
    "locale": "EN"
}

payload = {
    'EnableReassign': False,
    'Message': '',
    'Signers': json.dumps(signer_data),
    'Title': '{title}'
}

files = [
    ('Files', (
        'doc-2.pdf',
        open('{Your file path}', 'rb'),
        'application/pdf'
    ))
]

headers = {
    'accept': 'application/json',
    'X-API-KEY': '{Your API Key}'
}

response = requests.request("POST", url, headers=headers, data=payload, files=files)

print(response.text)

const axios = require('axios');
const FormData = require('form-data');
const fs = require('fs');
let data = new FormData();
data.append('EnableReassign', 'false');
data.append('Message', '');
data.append('Signers', '{\r\n        "name": "Hanky",\r\n        "emailAddress": "hankyWhites@cubeflakes.com",\r\n        "signerType": "Signer",\r\n        "formFields": [\r\n           {\r\n                "id": "string",\r\n                "name": "string",\r\n                "fieldType": "Signature",\r\n                "pageNumber": 1,\r\n                "bounds": {\r\n                  "x": 50,\r\n                  "y": 50,\r\n                  "width": 1,\r\n                  "height": 1\r\n                   },\r\n      "isRequired": true\r\n    }\r\n  ],\r\n  "locale": "EN"\r\n}');
data.append('Files', fs.createReadStream('{Your file path}'));
data.append('Title', '{title}');

let config = {
  method: 'post',
  maxBodyLength: Infinity,
  url: 'https://api.boldsign.com/v1/document/send',
  headers: { 
    'accept': 'application/json', 
    'X-API-KEY': '{Your API key}', 
    ...data.getHeaders()
  },
  data : data
};

axios.request(config)
.then((response) => {
  console.log(JSON.stringify(response.data));
})
.catch((error) => {
  console.log(error);
});