- [Instructor] Functions have arguments. What arguments does say for example, the factor function take? We can use the args function on the factor function. This tells us that this function has one input called X, second input called levels, a third called labels, and so. We can pass arguments by tag which means that we call or pass them by their names. So, this has a downside and upside the negative being that we need to know all of the arguments the upside being that we can call the names in any order. Say for example, I had defined a factor of the I knew the names and I call them as being X, levels, labels, ordered, true, And that returns the factor to the screen. I could have used partial calling whereby I am matching up to the number of letters given. So let's say I had inputted in this factor again, but instead chose to drop off a couple of letters from each of my different factors, inputs, I can still see that are smart enough to pick up what I have entered and recognises that the labels are defined by this B dollar and S. There is the potential for error in the instance where tags are not differentiated by partial names. 

Let's say I continue this journey of removing that is to help simplify my piece of code, I would see that there is a issue where the L for labels and levels overlaps and such that the tags are not differentiated sufficiently. So an error has arrived on the screen. We can pass arguments by position. It's useful when the arguments have an obvious interpretation. Say for example, in the instance that I had my whole labels and I could remove the names because we know their positions. However having seen the factor function you've now come to get used to what the T represents but if you had not seen the build up of this function, how would you know what this T represented?