Why are you printing this?
list_length = append()
print "There are %s items in the suitcase." % (list_length)
It should be something like,
print "There are %s items in the suitcase." % len(suitcase) # You don't need parentheses if it only has one argument
Then you can also do this,
print("The items in the Suitcase are: %s" % *suitcase)
When you put a
* infront of a variable that contains a list it unpacks all the data, you can use this to print the whole thing out. Also you can just add it with out the
* and it will print the whole list out.