Stage 1. ---------------------------------------------------(we might have a pre stage to this too)---------------------

-bash-3.2$ ls -ld template.py one
-rwx------ 1 dgerman faculty 37 Jul  6 04:28 one
-rw-r--r-- 1 dgerman faculty 14 Jul  6 04:27 template.py
-bash-3.2$ cat template.py
print "Hello"
-bash-3.2$ cat one
#!/usr/bin/python

import template


-bash-3.2$ ./one
Hello
-bash-3.2$

Stage 2. ---------------------------------------------------------------------------------------------------------------

-bash-3.2$ ls
one  template.py  template.pyc
-bash-3.2$ ls -l
total 24
-rwx------ 1 dgerman faculty  96 Jul  6 04:36 one
-rw-r--r-- 1 dgerman faculty 182 Jul  6 04:30 template.py
-rw-r--r-- 1 dgerman faculty 684 Jul  6 04:32 template.pyc
-bash-3.2$ cat template.py
class Engine(object):
  def __init__(self):
    print "New engine created."
  def start(self):
    print "I am starting now."
  def fun(self):
    print "This is the default fun."

-bash-3.2$ cat one
#!/usr/bin/python

import template

class One(template.Engine):
  pass

one = One()
one.start()
-bash-3.2$ ./one
New engine created.
I am starting now.
-bash-3.2$

Stage 3. ---------------------------------------------------------------------------------------------------------------

-bash-3.2$ cat template.py
class Engine(object):
  def __init__(self):
    print "New engine created."
  def start(self):
    print "I am starting now."
    self.fun()
  def fun(self):
    print "This is the default fun."

-bash-3.2$ cat one
#!/usr/bin/python

import template

class One(template.Engine):
  pass

one = One()
one.start()
-bash-3.2$ ./one
New engine created.
I am starting now.
This is the default fun.
-bash-3.2$

Stage 4. ---------------------------------------------------------------------------------------------------------------

-bash-3.2$ cat template.py
class Engine(object):
  def __init__(self):
    print "New engine created."
  def start(self):
    print "I am starting now."
    self.fun()
  def fun(self):
    print "This is the default fun."

-bash-3.2$ cat one
#!/usr/bin/python

import template

class One(template.Engine):
  def fun(self):
    print "I am the new fun."

one = One()
one.start()
-bash-3.2$ ./one
New engine created.
I am starting now.
I am the new fun.
-bash-3.2$

Minor modification: 

-bash-3.2$ ls -ld template.py
-rw-r--r-- 1 dgerman faculty 199 Jul  6 08:31 template.py
-bash-3.2$ cat template.py
class Engine(object):
  def __init__(self):
    print "New engine created."
  def execute(self):
    print "I am starting now."
    self.fun()
  def fun(self):
    print "This is the default fun."

-bash-3.2$ ls -ld one
-rwx------ 1 dgerman faculty 138 Jul  6 08:31 one
-bash-3.2$ cat one
#!/usr/bin/python

import template

class One(template.Engine):
  def fun(self):
    print "I am the new fun."

one = One()
one.execute()
-bash-3.2$ ./one
New engine created.
I am starting now.
I am the new fun.
-bash-3.2$

Stage 5. ---------------------------------------------------------------------------------------------------------------

-bash-3.2$ ls -ld template.py
-rw-r--r-- 1 dgerman faculty 553 Jul  6 08:38 template.py
-bash-3.2$ cat template.py
class Engine(object):
  def __init__(self):
    print "New engine created."
  def execute(self):
    s = self.retrieveState()
    if s.isEmpty():
      self.initializeState(s)
    else:
      self.updateState(s)
    self.saveState(s)
    self.reportState(s)
    self.getReadyforMoreInput()
  def retrieveState(self):
    return State()
  def initializeState(self, s):
    pass
  def saveState(self, s):
    pass
  def reportState(self, s):
    pass
  def getReadyforMoreInput(self):
    pass

class State(object):
  def isEmpty(self):
    return True
-bash-3.2$ ls -ld one
-rwx------ 1 dgerman faculty 138 Jul  6 08:31 one
-bash-3.2$ cat one
#!/usr/bin/python

import template

class One(template.Engine):
  def fun(self):
    print "I am the new fun."

one = One()
one.execute()
-bash-3.2$ ./one
New engine created.
-bash-3.2$

Stage 6 (final stage). --------------------------------------------------------------------------------------------------

-bash-3.2$ ls -l
total 24
-rwx------ 1 dgerman faculty 2541 Jul  6 09:28 one
-rw-r--r-- 1 dgerman faculty  656 Jul  6 09:26 template.py
-rw-r--r-- 1 dgerman faculty 1666 Jul  6 09:27 template.pyc
-bash-3.2$ cat template.py
import cgi

class Engine(object):
  def __init__(self):
    # print "New engine created."
    self.input = cgi.FieldStorage()
  def execute(self):
    s = self.retrieveState()
    if s.isEmpty() or self.reset():
      self.initializeState(s)
    else:
      self.updateState(s)
    self.saveState(s)
    self.reportState(s)
    self.getReadyforMoreInput()
  def retrieveState(self):
    return State()
  def initializeState(self, s):
    pass
  def saveState(self, s):
    pass
  def reportState(self, s):
    pass
  def getReadyforMoreInput(self):
    pass
  def reset(self):
    return False

class State(object):
  def isEmpty(self):
    return True
-bash-3.2$

-bash-3.2$ cat one
#!/usr/bin/python

import template, random

class One(template.Engine):
  def __init__(self):
    template.Engine.__init__(self)
  def retrieveState(self):
    # print "I am retrieving state..."
    (message, n1, n2, m1, m2) = ("", "", "", "", "")
    if self.input.has_key("message"): message = self.input["message"].value
    if self.input.has_key("n1"): n1 = self.input["n1"].value
    if self.input.has_key("n2"): n2 = self.input["n2"].value
    if self.input.has_key("m1"): m1 = self.input["m1"].value
    if self.input.has_key("m2"): m2 = self.input["m2"].value
    return MyState(message, n1, n2, m1, m2)
  def reset(self):
    reset = ""
    if self.input.has_key("reset"): reset = self.input["reset"].value
    return reset
  def initializeState(self, s):
    # print "I am being asked to initialize the state..."
    s.message = "Welcome"
    s.n1 = str(random.randrange(-50, 50))
    s.n2 = str(random.randrange(-50, 50))
    s.m1 = "0"
    s.m2 = "0"
  def updateState(self, s):
    # print "I am being asked to update the state based on input..."
    answer = ""
    if self.input.has_key("answer"): answer = self.input["answer"].value
    if answer and int(answer) == int(s.n1) + int(s.n2):
      s.message = "Very good."
      s.m1 = str(int(s.m1) + 1)
    else:
      s.message = "No, no, no."
    s.m2 = str(int(s.m2) + 1)
    s.message += "Score now: " + s.m1 + " out of " + s.m2
    s.n1 = str(random.randrange(-50, 50))
    s.n2 = str(random.randrange(-50, 50))
  def saveState(self, s):
    print "<form>"
    print "<input type=hidden name=message value=\"" + s.message + "\">"
    print "<input type=hidden name=n1 value=\"" + s.n1 + "\">"
    print "<input type=hidden name=n2 value=\"" + s.n2 + "\">"
    print "<input type=hidden name=m1 value=\"" + s.m1 + "\">"
    print "<input type=hidden name=m2 value=\"" + s.m2 + "\">"
  def reportState(self, s):
    print s.message + "<p>"
    print "What is " + s.n1 + " + " + s.n2 + "?"
  def getReadyforMoreInput(self):
    print "Answer: <input type=text name=answer> <p>"
    print "<input type=submit name=submit value=Proceed>"
    print "<input type=submit name=reset value=Reset>"
    print "</form>"

class MyState(template.State):
  def __init__(self, message, n1, n2, m1, m2):
    self.message = message
    self.n1 = n1
    self.n2 = n2
    self.m1 = m1
    self.m2 = m2
  def isEmpty(self):
    # print "I am being asked if I am empty..."
    return not self.message

print "Content-type: text/html\n\n"
one = One()
one.execute()
-bash-3.2$

My program works at:

http://silo.cs.indiana.edu:44063/cgi-bin/0706/one