How to access id or nickname value with python3:
response._content = b'{"id":44564,"nickname":'Demo'}
It looks like you're trying to read in a Json string and convert it to a dict, e.g.:
import json
# response._content = b'{"id":44564,"nickname":"Demo"}'
data = json.loads(response._content.decode('utf-8'))
# data = {'id': 44564, 'nickname': 'Demo'}