curl --request POST \
  --url https://omnicommerce.sg/ucp/v1/checkout-sessions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'UCP-Agent: <ucp-agent>' \
  --data '
{
  "line_items": [
    {
      "item": {
        "id": "00000000-0000-4000-8000-000000000001"
      },
      "quantity": 1
    }
  ]
}
'

const options = {
  method: 'POST',
  headers: {
    'UCP-Agent': '<ucp-agent>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    line_items: [{item: {id: '00000000-0000-4000-8000-000000000001'}, quantity: 1}]
  })
};

fetch('https://omnicommerce.sg/ucp/v1/checkout-sessions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://omnicommerce.sg/ucp/v1/checkout-sessions"

payload = { "line_items": [
        {
            "item": { "id": "00000000-0000-4000-8000-000000000001" },
            "quantity": 1
        }
    ] }
headers = {
    "UCP-Agent": "<ucp-agent>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

{
  "ucp": {},
  "id": "<string>",
  "line_items": [
    {
      "item": {
        "id": "<string>",
        "title": "<string>",
        "price": 123,
        "image_url": "<string>"
      },
      "quantity": 500
    }
  ],
  "status": "ready_for_complete",
  "currency": "<string>",
  "totals": [
    {}
  ],
  "buyer": {},
  "fulfillment": {},
  "payment": {},
  "order": {},
  "settlement": {}
}

{
  "ucp": {},
  "messages": [
    {}
  ]
}