use f as the as variable

Other examples use `f` as the response variable.

Author: picnixz

Doc/library/urllib.request.rst

@@ -1297,8 +1297,8 @@ Use of Basic HTTP Authentication::
    opener = urllib.request.build_opener(auth_handler)
    # ...and install it globally so it can be used with urlopen.
    urllib.request.install_opener(opener)
-   with urllib.request.urlopen('http://www.example.com/login.html') as r:
-       print(r.read().decode('utf-8'))
+   with urllib.request.urlopen('http://www.example.com/login.html') as f:
+       print(f.read().decode('utf-8'))
 
 :func:`build_opener` provides many handlers by default, including a
 :class:`ProxyHandler`.  By default, :class:`ProxyHandler` uses the environment
@@ -1316,8 +1316,8 @@ programmatically supplied proxy URLs, and adds proxy authorization support with
 
    opener = urllib.request.build_opener(proxy_handler, proxy_auth_handler)
    # This time, rather than install the OpenerDirector, we use it directly:
-   with opener.open('http://www.example.com/login.html') as response:
-      print(response.read().decode('utf-8'))
+   with opener.open('http://www.example.com/login.html') as f:
+      print(f.read().decode('utf-8'))
 
 Adding HTTP headers:
 
@@ -1328,8 +1328,8 @@ Use the *headers* argument to the :class:`Request` constructor, or::
    req.add_header('Referer', 'http://www.python.org/')
    # Customize the default User-Agent header value:
    req.add_header('User-Agent', 'urllib-example/0.1 (Contact: . . .)')
-   with urllib.request.urlopen(req) as r:
-       print(r.read().decode('utf-8'))
+   with urllib.request.urlopen(req) as f:
+       print(f.read().decode('utf-8'))
 
 
 :class:`OpenerDirector` automatically adds a :mailheader:`User-Agent` header to
@@ -1338,8 +1338,8 @@ every :class:`Request`.  To change this::
    import urllib.request
    opener = urllib.request.build_opener()
    opener.addheaders = [('User-agent', 'Mozilla/5.0')]
-   with opener.open('http://www.example.com/') as response:
-      print(response.read().decode('utf-8'))
+   with opener.open('http://www.example.com/') as f:
+      print(f.read().decode('utf-8'))
 
 Also, remember that a few standard headers (:mailheader:`Content-Length`,
 :mailheader:`Content-Type` and :mailheader:`Host`)