So y is equal to x, or this is f of x equals to x, or y is equal to this f of x right over there. Now, the derivative, actually let me just call that f of x, just to make it, not to confuse you. So this right over here is f of x is equal to x that I graphed right over here. y is equal to f of x, which is equal to x. And now let me graph the derivative, let me graph f prime of x. That's saying it's 1, that's saying it's 1 for all x, regardless of what x is, it's going to be equal to 1. Is this consistent with what we know about derivatives and slopes and all the rest?