import requests
from requests.auth import HTTPBasicAuth

theurl= 'example.com/file.txt'
username = 'username'
password = 'password'

r=requests.get(theurl, auth=HTTPBasicAuth(username, password))

import urllib.request
# Create an OpenerDirector with support for Basic HTTP Authentication...
auth_handler = urllib.request.HTTPBasicAuthHandler()
auth_handler.add_password(realm='PDQ Application',
                          uri='example.com/file.txt',
                          user='username',
                          passwd='password')
opener = urllib.request.build_opener(auth_handler)
# ...and install it globally so it can be used with urlopen.
urllib.request.install_opener(opener)