Python 3 - Add custom headers to urllib.request Request - python-3.x

Question

In Python 3, the following code obtains the HTML source for a webpage.
import urllib.request
url = "https://docs.python.org/3.4/howto/urllib2.html"
response = urllib.request.urlopen(url)
response.read()
How can I add the following custom header to the request when using urllib.request?
headers = { 'User-Agent' : 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)' }

Answer 1

The request headers can be customized by first creating a request object then supplying it to urlopen.
import urllib.request
url = "https://docs.python.org/3.4/howto/urllib2.html"
hdr = { 'User-Agent' : 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)' }
req = urllib.request.Request(url, headers=hdr)
response = urllib.request.urlopen(req)
response.read()
Source: Python 3.4 Documentation

Answer 2

import urllib.request
opener = urllib.request.build_opener()
opener.addheaders = [('User-agent', 'Mozilla/5.0')]
urllib.request.install_opener(opener)
response = urllib.request.urlopen("url")
response.read()
Should you wish to learn about the details you can refer to the python documentation: https://docs.python.org/3/library/urllib.request.html

Answer 3

#Using urllib.request, with urlopen, allows to open the specified URL.
#Headers can be included inside the urlopen along with the url.
from urllib.request import urlopen
url = "https://docs.python.org/3.4/howto/urllib2.html"
header = { 'User-Agent' : 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)' }
response = urlopen(url, headers=header)
response.read()