gistfile1.py

import requests
import json

def httpbin(*suffix):
    """Returns url for HTTPBIN resource."""
    return 'http://httpbin.org/' + '/'.join(suffix)

s = requests.session()
r = s.get(httpbin('cookies', 'set', 'a', '97'))
assert json.loads(r.text)['cookies'] ==  {'a': '97'}

c = requests.get(httpbin('cookies', 'set', 'c', '99')).cookies
# merge in the cookie with value 'c':
r = s.get(httpbin('cookies'), cookies=c)
assert json.loads(r.text)['cookies'], {'a': '97', 'c': '99'}

r = s.get(httpbin('cookies'))
# should this print 'a' and 'c', or just 'a'?
# currently prints 'a' and 'c'
print json.loads(r.text)['cookies']

a and c is correct.

To not send a cookie, you should be able to do this:

r = s.get(httpbin('cookies'), cookies={'c': None)