Using the Server API with Pyhon

I am trying to use the API with Conoha, which provides the server, but it has failed.
What I want to do is add servers using API.
https://www.conoha.jp/docs/compute-create_vm.html

The user token and image vm plan uuid have already been retrieved using a different API.
The page contains request parameters and request json.
I would like to post the header and json data at the same time, but is the code as below?
An error similar to the following appears:I'm not sure if the post is okay.

{'bad request':{'message':'Missing flavorRefattribute','code':400}

import requests
import json

json_data2 = {
    "server": {
        "imageRef": aaa,
        "flavorRef": bbb,
        "adminPass": "ccc"
    }
}
farm={"X-Auth-Token":dd}
    url4="https://compute.tyo1.conoha.io/v2/0ff2f439801145a6a44bfd9488fd360e/servers"
    res4=requests.post(url=url4,json=json_data2,data=json.dumps(parm))
    print("\n")
    print(less4.status_code)
    print(less4.json())
    print(less4)
    print()