Added Session04 and Session05 folders

Hello,

In session05 in my folder, I posted a program for the trigram homework. I created it without looking at the solution you posted (and forgot most of the details of what we reviewed in the previous class). Please, let me know what you think if you have time to look at it.
Thank you very much!
Michel.
this empty one just gets thrown away when you make the new one. Remember that names are bound to objects in python -- so when, in the next line, you do:
wordTuple = ....

the name wordTuple gets re-bound to a new object -- so having it set to an empty tuple does absolutely nothing....