curl --request OPTIONS \
  --url https://virtserver.swaggerhub.com/BangoProducts/Bango-Payment-API-v5/5.0.1/v5/transaction \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "bangoUserId": "987654321",
  "paymentItems": [
    {
      "itemName": "My item",
      "itemDescription": "My item description",
      "itemCategory": "1",
      "externalPaymentItemId": "abcd-1234",
      "submerchantReferenceKey": "submerchant1",
      "priceList": [
        {
          "grossAmount": "3.99",
          "currencyIso3": "USD",
          "financialBreakdown": {
            "taxAmount": "0"
          }
        }
      ]
    }
  ]
}
'

const options = {
  method: 'OPTIONS',
  headers: {Authorization: 'Basic <encoded-value>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    bangoUserId: '987654321',
    paymentItems: [
      {
        itemName: 'My item',
        itemDescription: 'My item description',
        itemCategory: '1',
        externalPaymentItemId: 'abcd-1234',
        submerchantReferenceKey: 'submerchant1',
        priceList: [
          {grossAmount: '3.99', currencyIso3: 'USD', financialBreakdown: {taxAmount: '0'}}
        ]
      }
    ]
  })
};

fetch('https://virtserver.swaggerhub.com/BangoProducts/Bango-Payment-API-v5/5.0.1/v5/transaction', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://virtserver.swaggerhub.com/BangoProducts/Bango-Payment-API-v5/5.0.1/v5/transaction"

payload = {
    "bangoUserId": "987654321",
    "paymentItems": [
        {
            "itemName": "My item",
            "itemDescription": "My item description",
            "itemCategory": "1",
            "externalPaymentItemId": "abcd-1234",
            "submerchantReferenceKey": "submerchant1",
            "priceList": [
                {
                    "grossAmount": "3.99",
                    "currencyIso3": "USD",
                    "financialBreakdown": { "taxAmount": "0" }
                }
            ]
        }
    ]
}
headers = {
    "Authorization": "Basic <encoded-value>",
    "Content-Type": "application/json"
}

response = requests.options(url, json=payload, headers=headers)

print(response.text)