If the create method is successful, the value associated to the request key will be a dictionary containing various information about the created request:
1-id: the request id
2-key: your private key for this request
For example code is like below.

from urllib import urlencode
from io import BytesIO
import pycurl
import json

CREATE_URL = "https://upgrade.odoo.com/database/v1/create"
CONTRACT = "M123456-abcdef"
AIM = "test"
TARGET = "8.0"
EMAIL = "john.doe@example.com"
FILENAME = "db_name.dump"

fields = dict([
    ('aim', AIM),
    ('email', EMAIL),
    ('filename', DB_SOURCE),
    ('contract', CONTRACT),
    ('target', TARGET),
])
postfields = urlencode(fields)

c = pycurl.Curl()
c.setopt(pycurl.URL, CREATE_URL)
c.setopt(c.POSTFIELDS, postfields)
data = BytesIO()
c.setopt(c.WRITEFUNCTION, data.write)
c.perform()

# transform output into a dict:
response = json.loads(data.getvalue())

# get http status:
http_code = c.getinfo(pycurl.HTTP_CODE)
c.close()

Note-Above values will be requested by the other methods (upload, process and status)