Hint for the methods to execute the different commands

• All the methods for the commands (except two) basically involved getting data from the user and then calling the appropriate command(s) from Inventory and/or Item.
• Two commands do not require input from the user, so they don't need the keyboard
• Two commands require a simple count-controlled loop (to do the number of times equal to the length of Inventory)
• Each loop needs a selection statement based on if the item is below the control level.