import requests
response = requests.post('http://httpbin.org/post', data={'key1':'value1'})
print(response.request.headers)
print(response.request.body)

import requests

def pretty_print_POST(req):
    print('{}\n{}\r\n{}\r\n\r\n{}'.format(
        '-----------START-----------',
        req.method + ' ' + req.url,
        '\r\n'.join('{}: {}'.format(k, v) for k, v in req.headers.items()),
        req.body,
    ))

req = requests.Request('POST','http://stackoverflow.com',headers={'X-Custom':'Test'},data='a=1&b=2')
prepared = req.prepare()
pretty_print_POST(prepared)

s = requests.Session()
resp = s.send(prepared)
print(resp.text)

from requests import Request, Session

s = Session()

req = Request('POST', url, data=data, headers=headers)
prepped = req.prepare()

# do something with prepped.body
prepped.body = 'No, I want exactly this as the body.'

# do something with prepped.headers
del prepped.headers['Content-Type']

resp = s.send(prepped,
    stream=stream,
    verify=verify,
    proxies=proxies,
    cert=cert,
    timeout=timeout
)

print(resp.status_code)