Part of the assignment for Session04

I am leaving tomorrow morning on a trip for work.  I'm checking in all of this week's assignment except for the trigrams portion, which I haven't gotten to yet.  I'm hoping that I will find the time to work on that over the next several days while I am away on travel, but I'm not sure what kind of progress I will be able to make.
Remember it is useful to just have one command in a try block, this way you can be fairly certain about what went wrong, if an exception is raised.