How to add a user/roles to DNG programmatically through API? Using Python requests

 I've been running into issues as to how to add users through the API. I've been looking at this website: https://jazz.net/wiki/bin/view/Main/DraftTeamProcessRestApi#Members_collection and specifically the section "Members collection: POST". I've copied the data in the request body example and edited it to fit my services. I then added it to an xml file and as a string. I've tried posting both of them but I keep getting a 400 "If the request body is invalid" error. Could anyone point me in the right direction for this? 

s = requests.Session()

eaders3 = {
    'Accept': 'application/rdf+xml',
    'OSLC-core-version': '2.0',
    'Content-Type': 'application/x-www-form-urlencoded',
    #'Content-Type': 'application/xml;charset=UTF-8',
}

with open('pa-members-to-add.xml', 'rb') as f:
    data = f.read().replace(b'\n', b'')

print(s.post(url3, headers=headers3, data=data))