completed stage 2 of about_objects.rb

* pivotal tracker id 75411404
* I learned that nil.to_s returns the empty string
completed stage 3 of about_objects.rb

* pivotal tracker id 75411404
* learned that nil.inspect returns 'nil'
completed stage 4 of about_objects.rb

* pivotal tracker id 75411404
* learned that every object has an id number, that is type Fixnum
completed stage 5 of about_objects.rb

* pivotal tracker id 75411404
* no two objects have the same id
completed stage 6 of about_objects.rb

* pivotal tracker id 75411404
* the whole numbers have fixed id's, namely the odd numbers. strange
completed all stages of about_objects.rb

* pivotal tracker id 75411404
* learned that you can clone objects, but it creates a
new object with a different id