Update a couple of code samples for Python 3

pep-3333.txt

@@ -230,8 +230,7 @@ support application developers.)
 Here are two example application objects; one is a function, and the
 other is a class::
 
-    # this would need to be a byte string in Python 3:
-    HELLO_WORLD = "Hello world!\n"  
+    HELLO_WORLD = b"Hello world!\n"  
 
     def simple_app(environ, start_response):
         """Simplest possible application object"""
@@ -281,9 +280,14 @@ server.
 
     import os, sys
 
-    def run_with_cgi(application):
+    enc, esc = sys.getfilesystemencoding(), 'surrogateescape'
 
-        environ = dict(os.environ.items())
+    def wsgi_string(u):
+        # Convert an environment variable to a WSGI "bytes-as-unicode" string
+        return u.encode(enc, esc).decode('iso-8859-1')
+
+    def run_with_cgi(application):
+        environ = {k: wsgi_string(v) for k,v in os.environ.items()}
         environ['wsgi.input']        = sys.stdin
         environ['wsgi.errors']       = sys.stderr
         environ['wsgi.version']      = (1, 0)