Colab Python web service : Cannot get expected return with json passing to REST API

Another silly mistake I made due carelessness .
I spent certain hours to just figure out the root-cause : Missing json.dumps when I pass the data.
Originally, I think put json content in header is OK...

#Call Rest API with json data
import requests
import json
import os

baseUrl = 'endpointAddr/api-link'

#Parameters
data = {
   "id":"1234568",
   "currency":"HKD",
   "amount":"1000"
}




#function to call
def callAPI():
    response = requests.post(baseUrl,headers={"Content-Type": "application/json","Authorization": "Bearer xxxxxxxxxxxxxxx"}, data=json.dumps(data))

    if response.status_code == 200:
       print('Access token test :' , response.json())
       authToken = response.json()['access_token']
       print('Access token:', authToken)
       return (authToken)
    else:
        print('Login failed with status code:', response.status_code , response.text)
        return (0)


#Main
response1 = callAPI()
print ('response 1 ' + response1)