We are writing a program that the manager of Joe's Automative Shop
will use to print service quotes for customers.  Here is a description
than an expert (maybe Joe) has written:

Joe's Automative Shop services foreign  cars and specializes in
servicing cars made by Mercedes, Porsche, and BMW.  When a customer
brings a car to the shop, the manager gets the customer's name,
address, and telephone number.  The manager then determines the make,
model, and year of the car, and gives the customer a service quote.
The service quote shows the estimated parts charges, estimated labor
charges, sales tax, and total estimated charges.

Things we may care about:
* Physical objects
* Role played by a person
* Results of a business event, e.g., a service quote
* Recordkeeping items, such as customer histories.

List of nouns (but don't include duplicates):
address 
BMW
car
cars
customer
etc.

Eliminate some nouns from the list:

Why?

1. some of the nouns refer to the same things

   car, cars, foreign cars - general idea of a car.  Just keep "car"

   Joe's Automative Shop and shop.  Just keep "shop".

2. some nouns we can ignore 

   We can cross shop off the list.  Our program only deals with
   different customers all at the same shop.  We aren't dealing with
   aspects of the shop itself.
   
   We can cross off the manager because the problem statement does not
   tell us to process any information about the manager.  If there were
   multiple managers and the problem description asked us to record
   which manager served which customers, then we wouldn't want to
   cross manager off.

   So, now we cross off:

   Joe's Automative Shop
   manager
   
3.  some of the nouns might represent objects, not classes.

    Mercedes, Porsche, and BMW can be eliminated as classes
    because they are instances of a car class.

    BMW
    Mercedes
    Porsche

4.  Some might represent simple values that can be assigned to a
    variable and do not require a class

    address
    estimated labor charges
    estimated parts charges
    make
    model
    name
    sales tax
    total estimated charges
    year
    etc.

What's left?

car
customer
service quote

We'll have 3 classes!

The Customer Class:
   attributes:
      __name, __address, __phone number
   methods:
      __init__()
      set_name(name)
      set_address(address)
      set_phone(phone)
      get_name()
      get_address()
      get_phone()

The Car Class
   attributes:
      __make, __model, __year
   methods:
      __init__()
      set_make(make)
      set_model(model)
      set_year(year)
      get_make()
      get_model()
      get_year()

The ServiceQuote Class:
    attributes:
      __parts_charges
      __labor_charges
    methods:
      __init__()
     set_parts_charges(charges)
     get_parts_charges()
     set_labor_charges(charges)
     get_labor_charges()
     get_sales_tax()
     get_total_charges()

[servicequotes.py]